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Showing 601 - 735 of 735 Journals sorted alphabetically
Scientific Reports     Open Access   (Followers: 85)
Sensors and Actuators B: Chemical     Hybrid Journal   (Followers: 18)
Sensors and Actuators Reports     Open Access   (Followers: 5)
Separation & Purification Reviews     Hybrid Journal   (Followers: 7)
Separation Science and Technology     Hybrid Journal   (Followers: 12)
Separations     Open Access   (Followers: 5)
Silicon Chemistry     Hybrid Journal   (Followers: 1)
Small Methods     Hybrid Journal   (Followers: 1)
Small Science     Open Access  
Small Structures     Hybrid Journal   (Followers: 1)
Smart Materials Research     Open Access   (Followers: 7)
SmartMat     Open Access  
Soft     Open Access  
Soft Nanoscience Letters     Open Access   (Followers: 1)
Solar RRL     Hybrid Journal  
Solid State Communications     Hybrid Journal   (Followers: 7)
Solid State Nuclear Magnetic Resonance     Hybrid Journal   (Followers: 3)
Solid State Sciences     Hybrid Journal   (Followers: 9)
Solvent Extraction and Ion Exchange     Hybrid Journal   (Followers: 7)
SPE Polymers     Open Access  
Spectral Analysis Review     Open Access  
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy     Hybrid Journal   (Followers: 15)
Spectrochimica Acta Part B: Atomic Spectroscopy     Hybrid Journal   (Followers: 17)
Spectroscopy and Spectral Analysis     Full-text available via subscription   (Followers: 1)
Starch / Staerke     Hybrid Journal   (Followers: 3)
Steel Research International     Hybrid Journal   (Followers: 22)
Structural Chemistry     Hybrid Journal   (Followers: 1)
Substantia     Open Access  
Supramolecular Chemistry     Hybrid Journal   (Followers: 5)
Supramolecular Materials     Full-text available via subscription   (Followers: 5)
Surface and Coatings Technology     Hybrid Journal   (Followers: 32)
Surface Science     Hybrid Journal   (Followers: 21)
Surface Science Reports     Full-text available via subscription   (Followers: 13)
Surfaces     Open Access   (Followers: 2)
Surfaces and Interfaces     Hybrid Journal   (Followers: 1)
Sustainable Chemical Processes     Open Access   (Followers: 3)
Sustainable Chemistry and Pharmacy     Full-text available via subscription   (Followers: 1)
Synfacts     Hybrid Journal   (Followers: 5)
Synlett     Hybrid Journal   (Followers: 44)
Synthesis     Hybrid Journal   (Followers: 53)
Talanta     Hybrid Journal   (Followers: 10)
Talanta Open     Full-text available via subscription   (Followers: 5)
Tecnología Química     Open Access  
Telematics and Informatics Reports     Full-text available via subscription   (Followers: 4)
Tenside Surfactants Detergents     Full-text available via subscription   (Followers: 2)
Tetrahedron     Hybrid Journal   (Followers: 77)
Tetrahedron Chem     Full-text available via subscription   (Followers: 6)
Tetrahedron Letters     Hybrid Journal   (Followers: 81)
The Alkaloids: Chemistry and Biology     Full-text available via subscription   (Followers: 1)
The All Results Journals : Chem     Open Access  
The Canadian Journal of Chemical Engineering     Hybrid Journal   (Followers: 5)
The Enzymes     Full-text available via subscription   (Followers: 2)
The Protein Journal     Hybrid Journal   (Followers: 5)
Theoretical and Experimental Chemistry     Hybrid Journal  
Theoretical Chemistry Accounts     Hybrid Journal   (Followers: 6)
Thermochimica Acta     Hybrid Journal   (Followers: 18)
Tip Revista Especializada en Ciencias Quimico-Biologicas     Open Access  
Topics in Current Chemistry     Hybrid Journal  
Toxicology International     Full-text available via subscription   (Followers: 5)
Toxicology Research     Partially Free   (Followers: 8)
Transition Metal Chemistry     Hybrid Journal   (Followers: 6)
Trends in Chemistry     Hybrid Journal  
Turkish Computational and Theoretical Chemistry     Open Access  
Ultrasonics Sonochemistry     Hybrid Journal   (Followers: 2)
Universal Journal of Chemistry     Open Access   (Followers: 1)
Vietnam Journal of Chemistry     Hybrid Journal  
Western Undergraduate Research Journal : Health and Natural Sciences     Open Access  
Wiley Interdisciplinary Reviews : Computational Molecular Science     Hybrid Journal   (Followers: 4)
World Journal of Chemical Education     Open Access   (Followers: 2)
X-Ray Spectrometry     Hybrid Journal   (Followers: 4)

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Synlett
Journal Prestige (SJR): 0.83
Citation Impact (citeScore): 2
Number of Followers: 44  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0936-5214 - ISSN (Online) 1437-2096
Published by Thieme Publishing Group Homepage  [233 journals]
  • SYNFORM ISSUE 2022/07

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      Synlett 2022; 33: A101-A117
      DOI: 10.1055/s-0040-1720564



      Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

      Artikel in Thieme eJournals:
      Inhaltsverzeichnis

      Synlett 2022; 33: A101-A1172022-06-15T07:39:08+01:00
      Issue No: Vol. 33, No. 11 (2022)
       
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      Synlett 2022; 33: V-
      DOI: 10.1055/s-0041-1737721



      Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

      Artikel in Thieme eJournals:
      Inhaltsverzeichnis

      Synlett 2022; 33: V-2022-06-15T07:36:28+01:00
      Issue No: Vol. 33, No. 11 (2022)
       
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      Synlett 2022; 33: V-
      DOI: 10.1055/s-0041-1737491



      Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

      Artikel in Thieme eJournals:
      Inhaltsverzeichnis

      Synlett 2022; 33: V-2022-05-31T00:00:00+01:00
      Issue No: Vol. 33, No. 10 (2022)
       
  • Ring Forming Approaches to para-Quinones: Toward a General
           Diels–Alder Disconnection

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      Authors: Budwitz; Jessica E., Newton, Christopher G.
      Abstract: para-Quinones feature extensively as targets and/or intermediates throughout a number of chemical and biological subdisciplines, highlighting the importance of efficient preparative methods. This Synpacts article provides an overview of ring forming approaches to para-hydroquinones and para-benzoquinones, concluding with our recent contribution concerning the development of 2,5-bis(tert-butyldimethylsilyloxy)furans as vicinal bisketene equivalents in the Diels–Alder reaction.1 Introduction2 Ring Forming Approaches to para-Quinones2.1 Hauser–Kraus Annulation2.2 Moore–Liebeskind Rearrangement2.3 Wulff–Dötz Reaction2.4 Oxidative Bergman Cyclization2.5 Diels–Alder Strategies2.5.1 Ketene–Enol Equivalents2.5.2 Bisketene Equivalents3 Toward an Improved Bisketene Equivalent4 Conclusion
      Citation: Synlett ; : -
      PubDate: 2022-06-27T15:34:08+01:00
      DOI: 10.1055/s-0041-1737966
       
  • Amine-Free O-Sulfonylation by a Combination of 4-Methylpyridine N-Oxide
           Catalyst with 4Å Molecular Sieves

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      Authors: Yoshida; Keisuke, Matsumoto, Yuma, Masuda, Juo, Kitagaki, Shinji
      Abstract: An amine-free sulfonylation of various alcohols was developed that uses 4-methylpyridine N-oxide in the presence of 4Å molecular sieves at room temperature. This mild method gives various sulfonylated products in high yields, and can be applied to base-sensitive substrates.
      Citation: Synlett ; : -
      PubDate: 2022-06-23T09:30:10+01:00
      DOI: 10.1055/a-1865-2970
       
  • Construction of Indole Skeletons through Direct Catalytic Three-Component
           Domino Reactions of Vinylarenes, Aldehydes, and Pronucleophiles

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      Authors: Hori; Fuka, Yoshimura, Tomoyuki, Matsuo, Jun-ichi
      Abstract: A synthesis of 3-alkyl-2-arylindoles was performed by sequential oxidation and reduction of 2-(2-nitrophenyl)ethanols that were prepared by base-catalyzed three-component reactions of vinylarenes, aldehydes, and various pronucleophiles, including nitroalkanes, thiols, and malonates. In addition to indoles, a selective synthesis of an N-hydroxyindole was accomplished. The highly nucleophilic character of transient benzylic anions in DMSO was also clarified for the three-component reactions.
      Citation: Synlett ; : -
      PubDate: 2022-06-23T09:30:05+01:00
      DOI: 10.1055/a-1865-2556
       
  • Amidation of α-Amino Acids Using
           Dichloro(methyl)(3,3,3-trifluoropropyl)silane and Imidazole without
           Conventional Protection and Deprotection of α-Amino Group

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      Authors: Nobuta; Tomoya, Morishita, Honoka, Suto, Yutaka, Yamagiwa, Noriyuki
      Abstract: Amidation of amino acids using dichloro(methyl)(3,3,3-trifluoropropyl)silane (MTFPSCl2) and imidazole is described. MTFPSCl2 activates the carboxy group and protects the α-amino group of amino acids. The amidation proceeded with 19 amino acids and 19 amines, including α-branched amines and anilines; the corresponding amino acid amides were synthesized in good-to-high yields (up to 96%) with low-to-no racemization.
      Citation: Synlett ; : -
      PubDate: 2022-06-22T15:05:26+01:00
      DOI: 10.1055/a-1865-1792
       
  • Polyoxometalate–Ionic Liquid-Catalyzed Ritter Reaction for Efficient
           Synthesis of Amides

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      Authors: Zhang; Lei, Chen, Bo, He, Peipei, Li, Guosong, Zhang, Lan-Cui, Gao, Shuang
      Abstract: A series of polyoxometalate-ionic liquid catalysts that combine the features of a polyoxometalate and an ionic liquid, with the introduction of acidity and miscibility, have been developed to promote the Ritter reaction. Among them, [BSmim]CuPW12O40 [BSmim = 1-methyl-3-(4-sulfobutyl)-1H-imidazol-3-ium] displayed the highest activity for the amidation of a variety of alcohols with nitriles, delivering the corresponding amide products in good to excellent yields. Furthermore, the reaction can be easily scaled up to a gram scale without losing efficiency. This process therefore provides an appealing way to prepare amides by a Ritter reaction using a polyoxometalate–ionic liquid-based catalyst.
      Citation: Synlett ; : -
      PubDate: 2022-06-21T15:29:55+01:00
      DOI: 10.1055/a-1854-9958
       
  • [2,3]-Sigmatropic Rearrangement of Arylhydroxylamines: Rapid Access to
           ortho-Sulfonylated Anilines

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      Authors: Liu; Yue, Xu, Gaofei, Gao, Hongyin
      Abstract: In the absence of transition-metal catalysts and additional oxidants, arylhydroxylamines can undergo an unconventional O-sulfinylation/[2,3]-sigmatropic rearrangement/rearomatization cascade with trifluoromethylsulfinyl chloride to rapidly and efficiently synthesize versatile ortho-sulfonylated aromatic amines. This Synpacts article describes the discovery, further study, and practical application of the rearrangement reactions in arylhydroxylamine compounds and highlights our recent advances in this area.1 Introduction2 Discovery of a New Reaction3 O-Sulfinylation of Arylhydroxylamines Followed by [2,3]-σ Rearrangement4 Conclusion
      Citation: Synlett ; : -
      PubDate: 2022-06-21T15:29:50+01:00
      DOI: 10.1055/a-1863-9090
       
  • Thiapillar[6]arene: Synthesis, Functionalization, and Properties

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      Authors: Etkind; Samuel I., Ichii, Shun, Romero, Nathan A., Swager, Timothy M.
      Abstract: The design and synthesis of new macrocycles with well-defined cavities represent a promising avenue for the development of new supramolecular hosts. Moreover, the ability to diversify a macrocycle through chemical manipulations enables the fine-tuning and tailoring of properties. In this report, the synthesis and functionalization of thiapillar[6]arene, a pillar[6]arene analogue in which the bridging methylene groups are replaced by sulfurs, are described. First, we demonstrate the scalable synthesis of the parent thiapillar[6]arene. Next, the diversification of thiapillar[6]arene is demonstrated via functionalization of the phenols and oxidation of the sulfur atoms. The solid-state structures of two thiapillar[6]arene derivatives are reported, and the effect of sulfur oxidation state on the macrocyclic conformation is discussed. All sulfone derivatives described were found to demonstrate high luminescence quantum yields (ΦF = 0.43–0.66) in CH2Cl2 with emission maxima between λ = 404 and 462 nm. Lastly, assessment of the electrochemical properties of the sulfone derivatives by square-wave voltammetry revealed electron-accepting ability owing to the oxidation of the sulfur atoms, with four reduction events observed for the analogues surveyed. Overall, this work implicates thiapillar[6]arene as a modular scaffold amenable for further applications in host–guest chemistry and sensing.
      Citation: Synlett ; : -
      PubDate: 2022-06-21T15:09:02+01:00
      DOI: 10.1055/s-0040-1719932
       
  • Catalytic Oxidations with ortho-Substituted Modified IBXs

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      Authors: Parida; Keshaba N., Moorthy, Jarugu Narasimha
      Abstract: o-Iodoxybenzoic acid (IBX) is an oxidation reagent that has surged into prominence in the last two decades. It is cost-effective, environmentally benign, and readily prepared from o-iodobenzoic acid. However, its insolubility in common organic solvents and explosive attributes upon impact and heating are debilitating disadvantages. The development of modified IBXs (mIBXs) that exhibit improved solubility and enhanced reactivity, and obviate explosive attributes by judicious manipulation of the structure of IBX has been an incessant endeavor. In this account, common organic solvent-soluble mIBXs developed in our research group are collated with a discussion of the rationale underlying the design principles. Steric build-up around the iodoxolone moiety that is responsible for strong intermolecular interactions within the crystal lattice of IBX constitutes the key consideration in the design and development of modified λ5-iodanes that are reactive and sparingly soluble in common organic solvents. In situ generation of mIBXs from precursor iodo-acids in the presence of Oxone® permits their employment as organocatalysts for facile oxidative transformations. Reactive mIBXs generated in situ from precursor modified iodo-acids (mIAs, II) in the presence of Oxone® may offer unrivaled prospects for cost-effective oxidations. Applications of mIBXs, generated in situ or otherwise, for efficient oxidations are consolidated.1 Introduction2 Design and Synthesis of Modified IBXs and their Precursors Iodo-Acids3 Catalytic Oxidations with Modified IBXs3.1 Oxidation of Alcohols3.2 Oxidation of 1,2-Diols3.3 Conversion of Diols into Lactones3.4 One-Pot Oxidative Cleavage of Olefins3.5 One-Pot Transformation of Olefins into α-Bromo- and α-Azidoketones4 Conclusions
      Citation: Synlett ; : -
      PubDate: 2022-06-21T15:08:58+01:00
      DOI: 10.1055/a-1813-7319
       
  • Diversity-Oriented Synthesis of Coumarin-Fused Cyclopentanones via a
           Nucleophilic Phosphine Controlled Cascade Reaction

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      Authors: Huang; Qi, Fu, Junfeng, Chang, Zhixin, Gan, Wenhao, Wang, Yongjiang, Han, Xiaoyu
      Abstract: A phosphine-promoted intermolecular annulation reaction of functionalized 3-benzoyl coumarin with alkynone has been disclosed. This reaction was found to be highly dependent on the nucleophilicity of the phosphine. Two classes of coumarin-fused cyclopentanones were selectively afforded in moderate to good yields with excellent diastereoselectivities under the mild reaction conditions.
      Citation: Synlett ; : -
      PubDate: 2022-06-20T13:39:53+01:00
      DOI: 10.1055/s-0041-1738399
       
  • One-Pot Synthesis of Glycosyl Chlorides from Thioglycosides Mediated by a
           Bromodiethylsulfonium Salt as a Mild Oxidant

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      Authors: Chooppawa; Tianchai, Janprasert, Penpicha, Padungros, Panuwat
      Abstract: The conventional synthesis of glycosyl chlorides from thioglycosides relies on sequential oxidation and chlorination. A one-pot synthesis of glycosyl chlorides is warranted as an alternative method. Here, we report a one-pot synthesis of glycosyl chlorides from thioglycoside precursors. The transformation was mediated at low temperatures by bromodiethylsulfonium bromopentachloroantimonate (BDSB) as a mild oxidant with Bu4NCl as an additive. Armed thioglycosides afforded the corresponding α-glycosyl chlorides in moderate to good yields under the optimized conditions. Low conversions and yields were obtained when the less-reactive disarmed thioglycosides were used. Unexpectedly, BDSB-mediated oxidation of thioglycosides without the addition of Bu4NCl also afforded the α-glycosyl chlorides in moderate yields. We suggest a mechanism involving the transfer of chloride ions from the nonnucleophilic bromopentachloroantimonate (SbCl5Br) anion to the oxocarbenium ion.
      Citation: Synlett ; : -
      PubDate: 2022-06-15T18:23:09+01:00
      DOI: 10.1055/a-1852-6889
       
  • Brønsted Acidic Ionic Liquid Catalyzed Three-Component Friedel–Crafts
           Reaction for the Synthesis of Unsymmetrical Triarylmethanes

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      Authors: Rinkam; Suttida, Senapak, Warapong, Watchasit, Sarayut, Saeeng, Rungnapha, Sirion, Uthaiwan
      Abstract: A convenient and practical method for the synthesis of unsymmetrical triarylmethanes was demonstrated through a one-pot three-component double Friedel–Crafts reaction of various aliphatic, aromatic, or heteroaromatic aldehydes with N,N-dialkylanilines and indoles by using a Brønsted acidic ionic liquid as the catalyst. This method was successfully applied under metal- and solvent-free conditions at 80 °C, affording the corresponding unsymmetrical triarylmethane products in moderate to high yields from a broad range of substrates. In addition, the mechanism of this reaction was studied by quantitative NMR analysis.
      Citation: Synlett ; : -
      PubDate: 2022-06-15T16:52:42+01:00
      DOI: 10.1055/a-1809-7768
       
  • Syntheses of Aristotelia Alkaloids: Reflections in the Chiral Pool

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      Authors: Argade; Malaika D., Riley, Andrew P.
      Abstract: The Aristotelia alkaloids are a family of monoterpene indole alkaloids possessing a characteristic azabicyclononane scaffold, which has been assembled by several synthetic methods. Herein we review those approaches that have adopted a biomimetic approach to unite heterocyclic synthons with chiral-pool monoterpenes. Throughout this discussion, the tendency of monoterpenes like α-pinene and limonene to undergo racemization is highlighted, revealing the challenges in developing stereospecific syntheses of these alkaloids. Finally, we provide a brief discussion of how these synthetic efforts have enabled the structural confirmation and elucidation of the Aristotelia alkaloids’ absolute configurations, including our own recent efforts to employ bioactivity data to deduce the naturally occurring configuration of the quinoline alkaloid aristoquinoline.1 Introduction2 Mercury-Mediated Ritter-Like Reactions3 Brønsted Acid Mediated Ritter-Like Reactions4 Synthesis of Aristoquinoline: Ritter-Like Reaction Approach5 Aza-Prins-Type Reaction in the Synthesis of Aristotelia Alkaloids6 Determination of Naturally Occurring Absolute Stereochemistry7 Conclusions
      Citation: Synlett ; : -
      PubDate: 2022-06-15T15:42:03+01:00
      DOI: 10.1055/a-1856-7334
       
  • 2-Iodoxybenzoic Acid–Dimethyl Sulfoxide (IBX-DMSO)-Promoted Oxidative
           Aromatization of Spiro[2.5]octa-4,7-dien-6-one

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      Authors: Li; Tong, Cui, Chaoxing, Zhang, Yuxia, Song, Xixi, Wang, Zechao, Chang, Junbiao
      Abstract: A 2-iodoxybenzoic acid (IBX)–dimethyl sulfoxide (IBX-DMSO)-promoted oxidative aromatization of spiro[2.5]octa-4,7-dien-6-ones has been developed. A series of substrates with various substitutions were transformed into oxidative aromatization products in good to excellent yields. This oxidative aromatization features environmentally friendly reagents, high efficiency, a broad substrate scope, broad functional-group tolerance, and mild reaction conditions.
      Citation: Synlett ; : -
      PubDate: 2022-06-15T15:41:59+01:00
      DOI: 10.1055/a-1863-8862
       
  • Construction of Successive Stereogenic Centers of ent-Kauranoid through an
           Oxidative Dearomatization/1,2-Shift Cascade

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      Authors: Imamura; Yuki, Mizutani, Hikaru, Nakada, Masahisa
      Abstract: The construction of the successive stereogenic centers, including an all-carbon quaternary stereogenic center, of ent-kauranoid through an oxidative dearomatization/1,2-shift cascade is described. The developed cascade reaction of a substrate bearing a trans-2-(p-methoxyphenyl)vinyl group as the migrating group afforded the desired product in 83% yield. The 1,2-shift in the cascade is strongly affected by a stereoelectronic effect. The X-ray crystal structure of a compound bearing four successive stereogenic centers in the fused-ring moiety of ent-kauranoid diterpene, which was prepared by the oxidative dearomatization/1,2-shift cascade and subsequent stereoselective transformations, is also reported.
      Citation: Synlett ; : -
      PubDate: 2022-06-15T14:49:39+01:00
      DOI: 10.1055/a-1855-3777
       
  • Amine Oxidation by Electrochemically Generated Peroxodicarbonate

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      Authors: Seitz; Ann-Katrin, van Lingen, Tim, Dyga, Marco, Kohlpaintner, Philipp J., Waldvogel, Siegfried R., Gooßen, Lukas J.
      Abstract: The N-oxidation of tertiary amines was achieved by using electrochemically generated peroxodicarbonate solutions as sustainable oxidizers. The presence of EDTA and 2,2,2-trifluoroacetophenone as a mediator was found to be crucial for converting water-insoluble substrates. Various tertiary amines were converted into their corresponding N-oxides in yields of up to 98%. The scope includes economically important surfactants and potential platform oxidizers.
      Citation: Synlett ; : -
      PubDate: 2022-06-15T14:49:35+01:00
      DOI: 10.1055/a-1860-3405
       
  • A Perspective on the Force-Induced Heterolytic Bond Cleavage in
           Triarylmethane Mechanophores

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      Authors: Hemmer; James R., Berrocal, José Augusto
      Abstract: Triarylmethane derivatives and their corresponding trityl carbocations are among the oldest chemical species synthesized and studied by chemists. The carbocationic platforms are particularly interesting due to their stability, high extinction coefficient, and tunable absorption of light in the visible spectrum, which can be achieved through structural modifications. These stable cations are traditionally obtained through heterolytic cleavage of judiciously designed, parent triarylmethanes by exposure to acids or UV light (λ < 300 nm), and methods based on electrochemistry or radiolysis. Our group has recently discovered that trityl carbocations can be generated also via mechanical stimulation of solid polymer materials featuring triarylmethane units as covalent crosslinks. In this Synpacts contribution, we expand on our previous finding by discussing some intriguing research questions that we aim to tackle in the immediate future.1 Introduction2 The Development of Our First Triarylmethane Mechanophore3 The Potential Reversibility of Triarylmethane Mechanophores4 A General Molecular Platform for Force-Induced, Scissile, Homolytic and Heterolytic Bond Cleavage'5 Conclusion
      Citation: Synlett ; : -
      PubDate: 2022-06-15T14:49:32+01:00
      DOI: 10.1055/a-1854-2131
       
  • Synthesis of Fluorinated 2-Benzylphthalazin-1(2H)-one, 1-Phthalazinamine,
           and 1-Alkoxy/Benzyloxyphthalazine Derivatives by an Ultrasonication Method
           

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      Authors: Pothireddy; Mohanreddy, Hazra, Gurupada, Babu, Penke Vijaya, Thirupathi, Barla, Dandela, Rambabu
      Abstract: Fluorinated heterocyclic compounds have been proven to exhibit interesting potential biological activities. Therefore, various fluorinated 2-benzylphthalazine-1(2H)-one and phthalazine-1-amine derivatives and nonfluorinated 1-alkoxy/benzyloxyphthalazines derivatives have been synthesized by an ultrasonication method. This protocol is more efficient than the conventional method in terms of its product yield and reaction handling and timelines.
      Citation: Synlett ; : -
      PubDate: 2022-06-09T20:12:41+01:00
      DOI: 10.1055/a-1846-5200
       
  • Asymmetric Michael Reaction of Malononitrile and α,β-Unsaturated
           Aldehydes Catalyzed by Diarylprolinol Silyl Ether

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      Authors: Hayashi; Yujiro, Hatano, Yutaro, Mori, Naoki
      Abstract: An asymmetric Michael reaction of malononitrile and α,β-unsaturated aldehydes catalyzed by a diarylprolinol silyl ether was developed. Michael products were obtained in good yields and with excellent enantioselectivities without the formation of overreaction products. As a malononitrile moiety can be transformed into an alkoxy or amino carbonyl moiety by oxidative transformation, α-chiral esters or amides with all-carbon quaternary centers can be synthesized with excellent enantioselectivities.
      Citation: Synlett ; : -
      PubDate: 2022-06-09T20:12:36+01:00
      DOI: 10.1055/a-1846-5007
       
  • Brønsted Base Catalyzed Conjugate Addition of β-Acylvinyl Anion
           Equivalents to α,β-Unsaturated Ketones

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      Authors: Kondoh; Azusa, Yamaguchi, Sho, Watanabe, Yushi, Terada, Masahiro
      Abstract: A Brønsted base catalyzed addition reaction of allyl sulfones having a diethoxyphosphoryloxy group, which are new precursors of β-acylvinyl anion equivalents, with α,β-unsaturated ketones was developed. The reaction proceeded efficiently under the influence of a phosphazene base as the catalyst. This is a rare example of a catalytic addition reaction of β-acylvinyl anion equivalents. A preliminary study on an asymmetric variant was also conducted with a chiral bis(guanidino)iminophosphorane catalyst.
      Citation: Synlett ; : -
      PubDate: 2022-06-09T20:12:33+01:00
      DOI: 10.1055/a-1827-5652
       
  • Silver-Catalyzed, One-Pot, Three-Component Difunctionalization of
           Quinones: Synthesis of Indole-Functionalized p-Iminoquinone Derivatives

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      Authors: Dong; Yu, Ye, Ji-Xian, Luo, Qi-Qi, Zheng, Yi, Zhou, Rui-Qi, Mei, Ting, Chen, Xiang-Long, Shi, Zhi-Chuan, Li, Zhong-Hui, He, Bing
      Abstract: A one-pot, three-component difunctionalization of quinones with indoles and arylamines has been developed to synthesize indole functionalized p-iminoquinones derivatives. The approach employed AgOAc as the catalyst in the presence of 3-chlorophenylboronic acid, giving a series of indole functionalized p-iminoquinones derivatives in moderate to good yields. This catalytic approach represents a step-economic and convenient strategy for the difunctionalization of quinones. A plausible reaction pathway has been proposed based on a series of control experiments.
      Citation: Synlett ; : -
      PubDate: 2022-06-09T20:12:29+01:00
      DOI: 10.1055/s-0040-1719929
       
  • Synthesis of Nitrogen Heterocycles by Domino C–N
           Coupling/Hydroamination Reactions

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      Authors: Langer; Peter
      Abstract: The present article presents a personalized Account on the synthesis of nitrogen heterocycles by domino C–N coupling/hydroamination reactions and related processes. The starting materials, 2-alkynyl-1-halohetarenes, are regioselectively available by Sonogashira reactions of various 1,2-dihalogenated heterocycles, such as thiophenes, benzothiophenes, furans and benzofurans, pyridines, quinolines, pyrimidines, and other ring systems. More complex products are formed by domino C–N coupling/hydroamination/C–H arylation reactions of 2-alkynyl-1-halohetarenes with 2-bromoanilines. In these reactions, not only two, but three bonds are formed in one step. In many cases, the products constitute new heterocyclic core structures and show interesting pharmacological or fluorescence properties.1 Introduction2 Domino C–N Coupling/Hydroamination Reactions3 Domino C–N Coupling/Hydroamination/C–H Arylation Reactions4 Conclusions
      Citation: Synlett ; : -
      PubDate: 2022-06-09T20:12:26+01:00
      DOI: 10.1055/s-0041-1738384
       
  • Unprecedented Rearrangement of β-Difluoroboryloxy Ethers: A Route to
           C-2 Alkyl-chromenones

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      Authors: Sahoo; Sushree Ranjan, Sarkar, Debayan, Somu, Prathap, Paul, Subhankar, Lönnecke, Peter
      Abstract: The addition of boron trifluoride etherate (BF3·OEt2) to allenic ketones has led to the isolation of the isolated boron difluoride enolates. The single-crystal structure of boron enolate has been solved. The unprecedented C1–C10 migration of (Z)-β-difluoroboryloxy ether derivatives is observed to deliver rearranged phenol derivatives which are functionalized to C-2 alkyl-chromenones. Interestingly the isolated boron enolates have exhibited significant anticancer properties.
      Citation: Synlett ; : -
      PubDate: 2022-06-09T20:12:19+01:00
      DOI: 10.1055/a-1833-8927
       
  • Formation of Seven-Membered Rings by Ring-Closing Metathesis of Vinyl
           Bromides

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      Authors: Ajavakom; Vachiraporn, Pandokrak, Potchanee, Salim, Sofia S., Moustafa, Gamal A. I., Bellingham, Richard K., Hill-Cousins, Joseph T., Ajavakom, Anawat, Brown, Richard C. D.
      Abstract: A Grubbs II catalyst mediated ring-closing metathesis (RCM) of monobrominated dienes is reported to proceed in moderate to good yields (40–80%) where the linking chain contains five atoms, leading to carbocyclic and heterocyclic seven-membered bromoolefins. Notably, RCM to form five-, six-, or eight-membered bromoolefins was unsuccessful, with the exception of one example where RCM afforded diethyl 3-bromocyclohex-3-ene-1,1-dicarboxylate. In this case, a bromomethyl-substituted cyclohexene was obtained as a byproduct. The utility of selected bromoolefin RCM products was demonstrated through their participation in Suzuki–Miyaura reactions. Vinylic halide exchange (Br → Cl) was noted as a side reaction under RCM conditions.
      Citation: Synlett ; : -
      PubDate: 2022-06-07T11:16:15+01:00
      DOI: 10.1055/a-1845-4195
       
  • Visible-Light-Induced Organocatalyzed [2+1] Cyclization of Alkynes and
           (Trifluoroacetyl)silanes

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      Authors: Zhou; Gang, Shen, Xiao
      Abstract: The synthesis of common cyclopropenes has been widely studied, but the synthesis of cyclopropenols is a significant challenge. Here, we highlight our recent work on the synthesis of trifluoromethylated cyclopropenols through a [2+1] cycloaddition reaction between alkynes and (trifluoroacetyl)silanes under visible-light-induced organocatalysis. The novel amphiphilic donor–acceptor carbenes derived from (trifluoroacetyl)silanes can react effectively with both activated and nonactivated alkynes. A broad substrate scope and a good functional-group tolerance have been achieved. Moreover, the synthetic potential of this reaction was highlighted by a gram-scale reaction and the one-pot diastereoselective synthesis of trifluoromethylated cyclopropanols.
      Citation: Synlett ; : -
      PubDate: 2022-06-07T11:16:11+01:00
      DOI: 10.1055/a-1840-5199
       
  • Bare Magnetite-Promoted Oxidative Hydroxylation of Arylboronic Acids and
           Subsequent Conversion into Phenolic Compounds

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      Authors: Cho; Hyun-A, Lee, Yong-Ki, Kim, Seung-Hoi
      Abstract: The simple combination of readily available, recoverable, and recyclable magnetite (Fe3O4) nanoparticles and an environmentally friendly oxidant (H2O2) induced the effective functional group transformation of arylboronic acids into their corresponding phenols under mild conditions. Moreover, subsequent treatment of the reaction intermediate with appropriate electrophiles was accomplished in a one-pot system, leading to the formation of halophenols and phenolic derivatives.
      Citation: Synlett ; : -
      PubDate: 2022-06-03T11:59:57+01:00
      DOI: 10.1055/s-0040-1719926
       
  • An Improved Scalable Process for the Synthesis of (S,S)-DACH-Ph Trost
           Ligand

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      Authors: Zhang; Yongda, Chong, Eugene, White, Jada A. H., Radomkit, Suttipol, Xu, Yibo, Kosnik, Stephanie C., Lorenz, Jon C.
      Abstract: An improved chemical process has been developed for the synthesis of (S,S)-DACH-Ph Trost ligand. The amidation of 2-diphenylphosphinylbenzoic acid and (S,S)-diaminocyclohexane is promoted by stoichiometric CDI and catalytic imidazole hydrochloride. The resulting product, (S,S)-DACH-Ph Trost ligand, is isolated as a white solid in 80% yield with>99% ee by simple filtration without column chromatography. The current facile process is also demonstrated on kilogram scale.
      Citation: Synlett ; : -
      PubDate: 2022-05-23T00:00:00+01:00
      DOI: 10.1055/s-0041-1738371
       
  • Late-Stage Functionalization for the Optimization of Reversible BTK
           Inhibitors

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      Authors: Tyagarajan; Sriram, Guiadeen, Deodial, Streckfuss, Eric, Gao, Xiaolei, Buevich, Alexei V., Doss, George, Liu, Jian, Vachal, Petr, Krska, Shane W.
      Abstract: Late-stage functionalization (LSF) enables medicinal chemists to quickly explore structure–activity relationships (SAR) of novel analogues derived from a fully elaborated parent structure. Using several known C–H functionalization chemistries, we have systematically applied the LSF strategy to modify different regions of a Bruton’s tyrosine kinase (BTK) reversible inhibitor lead series. This approach allowed for broad SAR exploration across several key subunits of the molecule at positions that were previously difficult to explore with traditional synthesis, providing analogues with high potency and improved pharmacokinetic properties. This case study illustrates both the promise and the challenges associated with applying LSF to complex lead molecules.
      Citation: Synlett ; : -
      PubDate: 2022-05-20T00:00:00+01:00
      DOI: 10.1055/s-0040-1719923
       
  • Transformations of Main-Group Organometallics Induced by Transition Metals

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      Authors: Hirao; Toshikazu, Amaya, Toru
      Abstract: The oxidative dehydrometallation of silyl or boron enolates is induced by palladium(II) catalyst to result in the versatile introduction of α,β-unsaturated carbon–carbon double bonds via palladium enolates. Selective oxidative cross- and homo-coupling reactions of silyl or boron enolates induced by vanadium(V) oxidant provide a selective synthetic method for accessing 1,4-dicarbonyl compounds in a nucleo­phile-nucleophile coupling mode. The ligand coupling reaction of main-group organometallic compounds induced by vanadium(V) oxi­dant provides a unique method for intramolecular carbon–carbon bond formation of nucleophiles. The last two reactions are a complementary strategy for the nucleophile-electrophile coupling reaction. The dehydrometallation and coupling reactions probably proceed through two- and one-electron oxidation processes, respectively.1 Introduction2 Palladium-Catalyzed Dehydrometallation3 Homo- and Cross-Coupling of Main-Group Organometallic Compounds4 Oxidative Ligand Coupling of Main-Group Organometallic Compounds5 Conclusion
      Citation: Synlett ; : -
      PubDate: 2022-05-10T00:00:00+01:00
      DOI: 10.1055/s-0041-1738071
       
  • Acetylenic Esters in Organic Synthesis

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      Authors: Hajinasiri; Rahimeh
      Abstract: Activated acetylenic substrates such as acetylenic esters and alkyl propiolates are very important in organic synthesis. Due to their electron deficiency, these compounds are widely used in combinatorial and multicomponent reactions, enabling the synthesis of a large variety of novel compounds. In addition, these substrates are powerful Michael acceptors and convenient dienophiles and dipolarophiles in Diels–Alder and 1,3-dipolar cycloaddition reactions. The addition of different nucleophiles, primarily phosphorus, nitrogen or sulfur, to the triple bonds of these substrates produces key intermediates, such as Tebby and Huisgen zwitterions, which can lead to designing pathways toward the generation of spirocyclic and polycyclic compounds. This account highlights recent studies on the chemistry of acetylenic esters and their applications in organic synthesis.1 Introduction2 Synthesis of Acyclic and Monocyclic Compounds3 Synthesis of Spirocyclic Compounds4 Synthesis of Polycyclic Compounds5 Conclusion
      Citation: Synlett ; : -
      PubDate: 2022-05-09T00:00:00+01:00
      DOI: 10.1055/s-0040-1719916
       
  • Methods for Determination of Absolute Configurations of Chiral Diols by
           THENA Ester and NMR Shift Difference

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      Authors: Dolsophon; Kulvadee, Soponpong, Jakapun, Kornsakulkarn, Jittra, Thongpanchang, Chawanee, Thongpanchang, Tienthong
      Abstract: Determination of the absolute configuration of chiral secondary diols by chiral derivatizing agent (CDA) and NMR shift difference is of great challenge due to the complication from the interference of the aromatic anisotropic shielding effect of the two CDAs in close proximity. In this work, tetrahydro-1,4-epoxynaphthalene-1-carboxylic acid (THENA) was introduced as an alternative CDA for diols to overcome such complexity. Since the deshielding effect of THENA is weaker than the shielding effect of other CDAs, THENA would allow the direct analysis of the chemical shift difference in determining the absolute configuration of the chiral diols. In addition, an analytical method based on Riguera’s model could also be used to confirm the assignment. With a good agreement between the assigned configuration based on both analytical models, the absolute configuration of the chiral diols could be assigned with reliability.
      Citation: Synlett ; : -
      PubDate: 2022-05-06T00:00:00+01:00
      DOI: 10.1055/s-0041-1737992
       
  • Advancing the Logic of Polymer Synthesis via Skeletal Rearrangements

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      Authors: Zhukhovitskiy; Aleksandr V., Ratushnyy, Maxim, Ditzler, Rachael A. J.
      Abstract: Polymers are ubiquitous materials that have driven technological innovation since the middle of the 20th century. As such, the logic that guides polymer synthesis merit considerable attention. Thus far, this logic has often been ‘forward-synthetic’, which constrains the accessible structures of polymer materials. In this article, we emphasize the benefits of ‘retrosynthetic’ logic and posit that the development of skeletal rearrangements of polymer backbones is central to the realization of this logic. To illustrate this point, we discuss two recent examples from our laboratory – Brook and Ireland–Claisen rearrangements of polymer backbones – and contextualize them in prior reports of sigmatropic rearrangements and skeletal rearrangements of polymers. We envision that further development of skeletal rearrangements of polymers will enable advances in not only the chemistry of such rearrangements and the logic of polymer synthesis, but also polymer re- and upcycling.
      Citation: Synlett ; : -
      PubDate: 2022-04-29T00:00:00+01:00
      DOI: 10.1055/s-0041-1737456
       
  • Electrochemical Reduction of Aldehydes and Ketones for the Synthesis of
           Alcohols and Diols under Ambient Conditions

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      Authors: Wang; Lei, Zhang, Xiao, Xia, Raymond Yang, Yang, Chao, Guo, Lin, Xia, Wujiong
      Abstract: A sustainable, practical, and direct strategy for the reduction of carbonyl compounds, including aldehydes and ketones, by an electrochemical pathway is presented, affording a variety of alcohols or diols as major products with decent yields. The reaction proceeds smoothly in the air at ambient temperatures with DABCO as the sacrificial reductant. Mechanistic studies revealed that direct electrochemical reduction followed by either protonation or radical–radical homocoupling is the main pathway.
      Citation: Synlett ; : -
      PubDate: 2022-04-25T00:00:00+01:00
      DOI: 10.1055/a-1833-9025
       
  • Enantioselective Synthesis of Axially Chiral Benzimidazoles ­Bearing a
           C–N axis via Pd-Catalyzed Buchwald–Hartwig ­Amination

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      Authors: Zhang; Peng, Feng, Jia, Liu, Ren-rong
      Abstract: Benzimidazole atropisomers bearing a C–N axis are privileged structural frameworks in pharmaceutical and natural products, thus appealing an increasing interest for its asymmetric synthesis. Here, we briefly discuss recent advances in the asymmetric synthesis of benzimidazole atropisomers with a C–N axis, with particular attention to our recently developed palladium-catalyzed intramolecular Buchwald–Hartwig amination strategy.
      Citation: Synlett ; : -
      PubDate: 2022-04-25T00:00:00+01:00
      DOI: 10.1055/a-1833-8979
       
  • Palladium-Catalyzed Synthesis of Heterocyclic Ring Systems by Combination
           of Regioselective C–C with Twofold C–N Couplings

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      Authors: Langer; Peter
      Abstract: The combination of regioselective palladium-catalyzed C–C with twofold C–N couplings allows for the synthesis of a variety of heterocyclic ring systems. Starting materials include thiophenes and benzothiophenes, pyrroles and indoles, furans and benzofurans, pyridines, quinolines and quinoxalines, complex heterocyclic systems and benzophenone derivatives. The products are in many cases complex polyheterocyclic systems, which are not readily available by other methods or, in a number of cases, were not described in the literature before. They are of pharmacological relevance or interesting in the field of material science. Products include thieno[3,2-b:4,5-b′]diindoles, thieno[3,2-b]indoles, thieno[3,4-b]indoles, 5,10-dihydroindolo[3,2-b]indoles, furo[3,2-b:4,5-b′]diindoles, benzo[4,5]furo[3,2-b]indoles, 5,7-dihydropyrido[3,2-b:5,6-b′]diindoles, 5,7-dihydropyrido[2,3-b:6,5-b´]diindoles, α-, β-, γ- and δ-carbolines, indolo[3,2-b]quinolines, indolo[2,3-b]quinolines, indolo[3,2-c]quinolines, indoloquinoxalines, pyrido[2′,1′:2,3]imidazo[4,5-b]indoles, thiadiazolo[2′,3′:2,3]imidazo[4,5-b]indoles, benzo[b]carbazolediones, acridones and thieno[3,2-b]quinolones.Contents1 Introduction2 Thiophenes and Benzothiophenes3 Pyrroles and Indoles4 Furans and Benzofurans5 Pyridines6 Quinolines and Quinoxalines7 Complex Heterocyclic Systems8 2,3-Dibromonaphthoquinone9 Benzophenone Derivatives10 Conclusions
      Citation: Synlett ; : -
      PubDate: 2022-04-25T00:00:00+01:00
      DOI: 10.1055/s-0040-1719918
       
  • Flexible Piezoionic Strain Sensors toward Artificial Intelligence
           Applications

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      Authors: Lu; Chao, Chen, Xi
      Abstract: Flexible piezoionic strain sensors are playing an important role in the field of smart electronic and artificial intelligence. The high sensitivity and superior flexibility make it possible to detect various strain and stress from macro- to microscale precisely. Here, recent progress on flexible piezoionic strain sensors has been summarized into several sections, including sensing mechanism, material engineering, and smart applications. In each section, we present typical scientific works and discuss corresponding critical results. This Account aims to provide broad views for researchers with different academic backgrounds, and then promotes the development of flexible piezoionic strain sensors. Finally, existing challenges and opportunities have been presented to expedite further research works and practical applications of flexible piezoionic strain sensors.1 Introduction2 Sensing Mechanism of Flexible Piezoionic Strain Sensors3 Material Engineering for Flexible Piezoionic Strain Sensors3.1 Electrolyte Materials for Flexible Piezoionic Strain Sensors3.2 Electrode Materials for Flexible Piezoionic Strain Sensors4 Smart Applications of Flexible Piezoionic Strain Sensors toward Artificial Intelligence5 Conclusion and Perspective
      Citation: Synlett ; : -
      PubDate: 2022-04-25T00:00:00+01:00
      DOI: 10.1055/s-0041-1737455
       
  • An Efficient Route to Branched Allylsilanes through Copper-Catalyzed
           Allene Hydrosilylation Using Readily Available Silanes

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      Authors: Liu; Xiao-Tao, Chen, Jun-Jia, Zhan, Zhuang-Ping
      Abstract: A CuCl-catalyzed hydrosilylation of allenes with PhSiH3 has been developed. It is the first example of using readily available cheap silane reagents to generate branched allylsilanes in copper-catalyzed allene hydrosilylation. This base-metal catalyst offered an atom-economical and efficient route to branched allylsilanes with excellent regioselectivity.
      Citation: Synlett ; : -
      PubDate: 2022-04-20T00:00:00+01:00
      DOI: 10.1055/a-1829-8574
       
  • Manganese-Catalyzed Synthesis of Imines from Primary Alcohols and
           (Hetero)Aromatic Amines

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      Authors: Raydan; Daniel, Friães, Sofia, Viduedo, Nuno, Santos, A. Sofia, Gomes, Clara S. B., Royo, Beatriz, Marques, M. Manuel B.
      Abstract: Herein, we describe the synthesis of a wide variety of imines through oxidative coupling of alcohols and aromatic amines catalyzed by Mn complexes bearing N^N triazole ligands. A wide variety of imines in excellent yields (up to 99%) have been prepared. Mn-based catalysts proved to be highly efficient and versatile, allowing for the first time the preparation of several imines containing N-based heterocycles.
      Citation: Synlett ; : -
      PubDate: 2022-04-19T00:00:00+01:00
      DOI: 10.1055/a-1828-1678
       
  • Divergent Thio/Selenolactonization of Styrene-Type Carboxylic Acids and
           Amides: Synthesis of Chalcogenated Isobenzofuran-1 (3H)-ones and
           Isochroman-1-ones

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      Authors: Goutham; Kommuru, Zhang, Jingran, Ouyang, Yaxin, Du, Yunfei, Zhao, Kang
      Abstract: A divergent synthesis of isobenzofuran-1(3H)-one and 3,4-dihydroisochroman-1-one derivatives has been realized through the reaction of o-alkenyl benzoic acids/amides with PhICl2 and diphenyl disulfides/diselenides. Depending on the substitution type of the o-alkenyl benzoic acid or amide, this metal-free intramolecular oxychalcogenation approach regioselectively affords isobenzofuran-1(3H)-ones or 3,4-dihydroisochroman-1-ones through 5-exo-trig or 6-endo-trig cyclization processes, respectively.
      Citation: Synlett ; : -
      PubDate: 2022-04-18T00:00:00+01:00
      DOI: 10.1055/a-1827-6915
       
  • Electrochemical C–H Functionalization of Cyclic Amines

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      Authors: Feng; Tian, Wang, Siyi, Qiu, Youai
      Abstract: Functionalized cyclic amines are essential structural motifs in synthetic chemistry and pharmaceutical chemistry, and Shono-type oxidation is a well-developed electrochemical approach for the synthesis of α- amines. In sharp contrast, electrochemically driven direct β-C(sp3)–H functionalization of amines has been far proven elusive. Herein, we outline the recent advances in this field and highlight our group’s effort to achieve electrochemical β-C(sp3)–H functionalization assisted by ferrocene as molecular electrocatalyst under mild conditions.1 Introduction2 Case studies of α-Functionalization (Shono-Type Oxidation)3 Electrochemical β-C(sp3)–H Acylation4 Conclusion
      Citation: Synlett ; : -
      PubDate: 2022-04-18T00:00:00+01:00
      DOI: 10.1055/a-1828-1217
       
  • Accelerated Decomposition of Potassium Permanganate in Ferrocenium Ion as
           

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      Authors: Chumkaeo; Peerapong, Poonsawat, Thinnaphat, Yunita, Isti, Temnuch, Natcha, Meechai, Titiya, Kumpan, Nuttapong, Khamthip, Achjana, Chuaitammakit, Laksamee Chaicharoenwimolkul, Chairam, Sanoe, Somsook, Ekasith
      Abstract: Ferrocenium-doped manganese(IV) oxide (Fc+/MnO2) was synthesized through accelerated decomposition of KMnO4 in the presence of ferrocenium ion (Fc+) generated by concentrated sulfuric acid. The corresponding catalysts enabled highly efficient oxidation of alcohols with aldehyde or ketone.
      Citation: Synlett ; : -
      PubDate: 2022-04-05T00:00:00+01:00
      DOI: 10.1055/a-1817-1038
       
  • Kinetic Resolution of dl-Hydrobenzoins Catalyzed by Copper(II) Complexes
           of C 2-Symmetric Thiophene-Derived Ligands

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      Authors: Mansawat; Woraluk, Yukhet, Phanomsak, Bhanthumnavin, Worawan, Reiser, Oliver, Vilaivan, Tirayut
      Abstract: C 2-Symmetrical chiral amino alcohol ligands with a central thiophene moiety were shown to be effective in combination with CuCl2 for the asymmetric acylation of dl-hydrobenzoins. In contrast to previously developed chiral ligands, readily available acetyl chloride and acetic anhydride can be used as reagents, in addition to benzoyl chloride, giving rise to the corresponding monoacylated products in up to 99% ee (S = 532).
      Citation: Synlett ; : -
      PubDate: 2022-04-04T00:00:00+01:00
      DOI: 10.1055/a-1815-7091
       
  • Expedient Access to Indolyl-Substituted Tri- and Diarylmethanes and
           

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      Authors: Yimyaem; Jirapat, Chantana, Chayamon, Boonmee, Suthimon, Jaratjaroonphong, Jaray
      Abstract: An expedient access to a series of nonsymmetrical bis(indolyl)methanes (BIMs) through transindolylation of readily available symmetrical 3,3′-BIMs with various indoles catalyzed by silica-supported sulfuric acid has been established. This approach not only provides a useful strategy for the synthesis of structurally diverse BIMs, but also provides examples of nucleophilic substitution of BIMs with aromatic and nonaromatic π-systems, leading to a library of indolyl-substituted tri- and diarylmethanes. Moreover, this method was successfully applied in the first total synthesis of the 2,3′-BIM alkaloid (±)-colletotryptin E in three steps with an overall yield of 46%. The features of this procedure include a metal-free process, an inexpensive and environmentally friendly catalyst, mild reaction conditions, broad functional-group tolerance, good yields, and gram-scalable preparations.
      Citation: Synlett ; : -
      PubDate: 2022-04-01T00:00:00+01:00
      DOI: 10.1055/s-0040-1719915
       
  • Pillar[4]arene[1]thioarenes: Synthesis and Host–Guest Binding
           Properties

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      Authors: Khanthong; Adisorn, Khamphaijun, Korawit, Ruengsuk, Araya, Docker, Andrew, Limpanuparb, Taweetham, Tantirungrotechai, Jonggol, Bunchuay, Thanthapatra
      Abstract: The synthesis and characterization of a novel class of pillar[4]arene[1]thioarenes (P[4]A[1]SMe) are reported. An oxidation–thionation strategy was used to replace a single dialkoxybenzene panel in the parent pillar[5]arene. 1H NMR spectroscopic titration experiments, supported by density functional theory computational studies, revealed that P[4]A[1]SMe show starkly modulated host–guest binding properties for electron-deficient aliphatic guests.
      Citation: Synlett ; : -
      PubDate: 2022-03-23T00:00:00+0100
      DOI: 10.1055/a-1806-5999
       
  • Diastereoselective Synthesis of Tetrahydrofurano[2,3-g]indolizidines and
           8-Aminoindolizidines from l-Asparagine

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      Authors: Kuntiyong; Punlop, Inprung, Nantachai, Attanonchai, Sineenart, Kheakwanwong, Wichita, Bunrod, Pijitra, Akkarasamiyo, Sunisa
      Abstract: 8-Aminoindolizidines were synthesized from l-asparagine as the chiral starting material. The key dibenzylamino succinimide intermediate was synthesized in two steps. Three homologs of chiral hydroxy lactams tethered with hydroxyalkenes were synthesized from the succinimide through a sequence involving N-alkylation, cross-olefin metathesis, and hydride reduction. The dibenzylamino group gave stereocontrol of the key N-acyliminium ion cyclization of these hydroxy lactams. 5-Substituted aminoindolizidines were synthesized with high diastereoselectivity at C6. A tandem cyclization of an N-(6-hydroxyhex-3-en-1-yl) γ-hydroxy lactam resulted in the formation of a tetrahydrofurano[2,3-g]indolizidine system.
      Citation: Synlett ; : -
      PubDate: 2022-03-23T00:00:00+0100
      DOI: 10.1055/a-1806-6089
       
  • 2,3-Diaryl-1,1,4,4-tetracyanobutadienes as Colorimetric Sensors for
           Sulfide Ion in Aqueous Media

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      Authors: Pham; Quynh Nguyen Nhu, Silpcharu, Komthep, Vchirawongkwin, Viwat, Sukwattanasinitt, Mongkol, Rashatasakhon, Paitoon
      Abstract: Two diaryl derivatives of 1,1,4,4-tetracyanobuta-1,3-diene were synthesized for use as colorimetric ion sensors in aqueous media. The key synthetic step involved a [2+2]-cycloaddition/retro-cycloaddition between an electron-rich diarylethyne and electron-deficient tetracyanoethene. The compound bearing two sulfonamide groups showed good selectivity toward hydrogen sulfide ion, with a detection limit of 15.5 μM. The use of this sensor for the quantitative analysis of hydrogen sulfide ion in water samples was successfully demonstrated.
      Citation: Synlett ; : -
      PubDate: 2022-03-23T00:00:00+0100
      DOI: 10.1055/a-1806-6258
       
  • Synthesis of (Z)-Cinnamate Esters by Nickel-Catalyzed Stereoinvertive
           Deoxygenation of trans-3-Arylglycidates

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      Authors: Akkarasamiyo; Sunisa, Chitsomkhuan, Saranya, Buakaew, Supawadee, Samec, Joseph S. M., Chuawong, Pitak, Kuntiyong, Punlop
      Abstract: We report a stereoinvertive deoxygenation of trans-3-arylglycidates as an alternative route to access thermodynamically less stable (Z)-cinnamate esters by using nickel triflate and triphenylphosphine. Broad functional-group tolerance was observed, with trans-3-arylglycidates containing methyl, methoxy, halo, or nitro groups affording the corresponding (Z)-cinnamate esters in high yields and with moderate to high E/Z ratios.
      Citation: Synlett ; : -
      PubDate: 2022-03-21T00:00:00+0100
      DOI: 10.1055/s-0040-1719911
       
  • One-Pot Synthesis of 2-Arylindole Derivatives under Transition-Metal-Free
           Conditions

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      Authors: Kraikruan; Panitan, Rakchaya, Intouch, Sang-aroon, Pattarapon, Chuanopparat, Nutthawat, Ngernmeesri, Paiboon
      Abstract: A new and simple method for preparing 2-arylindole derivatives under transition-metal-free conditions has been developed. When N-(2-methyl-3-nitrophenyl)acetamide was treated with 2-fluorobenzaldehydes in the presence of Cs2CO3 in DMF at 60 °C, the desired indoles were typically obtained in moderate to good yields (up to 83%). When other aniline substrates were employed, only a Knoevenagel condensation occurred, giving the corresponding diarylethenes in moderate to excellent yields.
      Citation: Synlett ; : -
      PubDate: 2022-03-14T00:00:00+0100
      DOI: 10.1055/a-1796-9647
       
  • Direct Synthesis of Coumarin Derivatives from Alkynoic Esters via Dual
           Organocatalysis

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      Authors: Saejong; Peerawat, Somprasong, Siriphong, Rujirasereesakul, Chaiwat, Luanphaisarnnont, Torsak
      Abstract: An efficient synthetic method for coumarin derivatives was developed using a dual organocatalytic reaction. A combination of p-toluenesulfonic acid monohydrate and piperidine was found to efficiently catalyze the cyclization between salicylaldehydes and alkynoic esters to give various coumarin derivatives in good yield and high selectivity. Mechanistic and kinetic data suggested that the conjugate addition between piperidine and alkynoic esters played a crucial role in the reaction mechanism.
      Citation: Synlett ; : -
      PubDate: 2022-03-14T00:00:00+0100
      DOI: 10.1055/a-1797-0386
       
  • The Design and Synthesis of Phenylcyclopropane-Based Secondary Amine
           Catalysts and Their Applications in Asymmetric Reactions

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      Authors: Takeshima; Aika, Kano, Taichi
      Abstract: Most chiral secondary amine catalysts are usually synthesized from chiral amino acids and their derivatives. On the other hand, amine catalysts based on a binaphthyl backbone have previously been developed, and show unique chemo- and stereoselectivity in several asymmetric reactions. However, in spite of their utility, the applications of binaphthyl-based amines in asymmetric reactions are still rare due to their synthetic inefficiency. In this context, we have designed amine catalysts possessing a phenylcyclopropane scaffold as a novel chiral motif. These novel catalysts can be synthesized easily and construct a similar chiral environment to that of binaphthyl-based amine catalysts. In addition, a phenylcyclopropane-based amino sulfonamide is found to be an effective catalyst for syn-selective Mannich reactions and conjugate additions using alkynyl Z-ketimines.1 Introduction2 Design and Synthesis of Novel Chiral Secondary Amine Catalysts3 Performance Evaluation of Phenylcyclopropane-Based Amine Catalysts4 Development of Asymmetric Reactions Catalyzed by a Novel Chiral Amino Sulfonamide5 Conclusions
      Citation: Synlett ; : -
      PubDate: 2022-03-13T00:00:00+0100
      DOI: 10.1055/a-1796-7387
       
  • Ionic Liquid Driven Nucleophilic Substitution of Squaric Acid to
           Squaramides

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      Authors: Soonthonhut; Siraporn, Acharasatian, Peera
      Abstract: Solubility is a crucial encumbrance for the synthesis of squaramides through nucleophilic substitution of squaric acid. The reactions must be performed in an aqueous medium since squaric acid is insoluble in virtually all organic solvents. The scope of amine nucleophiles was consequently restricted to those amines soluble in water. Owing to remarkable solvating ability of ionic liquid, reactions of squaric acid with a variety of structurally diverse amine nucleophiles were achieved. Interestingly, a catalyst-free reaction in 1-butyl-3-methylimidazolium chloride or [bmim]Cl could produce squaramides up to 99% yield. With the same efficacies, [bmim]Cl could be reused for at least three cycles. The catalyst-free, ionic liquid mediated approach expanded the reactant scope and offered a simple, efficient, and environmentally friendly synthesis of squaramides.
      Citation: Synlett ; : -
      PubDate: 2022-03-11T00:00:00+0100
      DOI: 10.1055/a-1795-8322
       
  • Synthesis of Eleven-Membered Cyclic Urea Fused Quinazolinones

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      Authors: Saebang; Yotsakorn, Kaeobamrung, Juthanat, Rukachaisirikul, Vatcharin
      Abstract: Straightforward synthesis of quinazolinones having N-fused medium-sized ring urea was accomplished. Key intermediates were tert-butyl {2-[4-oxo-2-(4-oxopentyl)quinazolin-3(4H)-yl]ethyl}carbamates derived from copper-catalyzed domino reaction of tert-butyl [2-(2-iodobenzamido)ethyl]carbamates and cyclic enaminones. Steric hindrance of cyclic enaminones played an important role in the formation of quinazolinone ring. The eleven-membered ring urea moiety was readily achieved by direct cyclization using 1,1′-carbonyldiimidazole (CDI) of diamino intermediate generated by readily reductive amination and deprotection of tert-butyl {2-[4-oxo-2-(4-oxopentyl)quinazolin-3(4H)-yl]ethyl}carbamates.
      Citation: Synlett ; : -
      PubDate: 2022-03-09T00:00:00+0100
      DOI: 10.1055/a-1793-1321
       
  • Decarboxylation of Paraconic Acids by a Silver(I) Nitrate/Persulfate
           Combination: An Entry to β-Nitro- and β-Hydroxy γ-Butyrolactones

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      Authors: Phae-nok; Supasorn, Kuhakarn, Chutima, Leowanawat, Pawaret, Reutrakul, Vichai, Soorukram, Darunee
      Abstract: Decarboxylative transformations of paraconic acids, a class of γ-butyrolactones containing a carboxylic acid group at the β-position as their characteristic functionality, by using a combination of AgNO3/K2S2O8 were investigated. The dual function of AgNO3 as an initiator of the decarboxylation process and as a source of nitrogen dioxide radicals that react with aliphatic carboxylic substrates is reported for the first time. Starting from paraconic acids, β-nitro- and β-hydroxy γ-butyrolactones were obtained in good combined yields (41–85%) with moderate selectivity in a one-pot operation. The reactions were completed within an acceptable reaction time (two hours) under mild conditions that were tolerated by the γ-butyrolactone core. This study provides a direct and site-specific entry to β-nitro- and β-hydroxy γ-butyrolactones, which are important precursors in organic transformations.
      Citation: Synlett ; : -
      PubDate: 2022-03-09T00:00:00+0100
      DOI: 10.1055/a-1792-7169
       
  • Total Synthesis and Cytotoxic Activity of 7-O-Methylnigrosporolide and
           Pestalotioprolide D

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      Authors: Thiraporn; Aticha, Iawsipo, Panata, Tadpetch, Kwanruthai
      Abstract: A convergent total synthesis of 7-O-methylnigrosporolide and pestalotioprolide D has been accomplished in 17 linear steps and overall yields of 1.7% and 2.6%, respectively, starting from (S)-propylene oxide and (S)-benzyl glycidyl ether. Our synthesis exploited an acetylide addition and a Shiina macrolactonization to assemble the macrocycle, a Lindlar reduction, and Wittig and Still–Gennari olefinations to construct the three alkene groups, as well as a Jacobsen hydrolytic kinetic resolution to install the stereogenic center. The selection of the silyl protecting group of the C-4 alcohol was crucial for the final deprotection step. Our synthesis also led to a hypothesis that pestalotioprolide D might be an artifact of 7-O-methylnigrosporolide. The cytotoxic activities of the two synthetic compounds against six human cancer cell lines were evaluated. Synthetic pestalotioprolide D showed more potent cytotoxic activity than 7-O-methylnigrosporolide against all the cancer cell lines tested, and the SiHa cervical cancer cell line was the most sensitive to both synthetic compounds.
      Citation: Synlett ; : -
      PubDate: 2022-03-09T00:00:00+0100
      DOI: 10.1055/a-1792-8402
       
  • Catalytic Kinetic Resolution and Desymmetrization of Amines

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      Authors: Liu; Wei, Wang, Donglei, Zhang, Dekun, Yang, Xiaoyu
      Abstract: Optically active amines represent critically important subunits in bioactive natural products and pharmaceuticals, as well as key scaffolds in chiral catalysts and ligands. Kinetic resolution of racemic amines and enantioselective desymmetrization of prochiral amines have proved to be efficient methods to access enantioenriched amines, especially when the racemic or prochiral amines were easy to prepare while the chiral ones are difficult to be accessed directly. In this Account, we systematically summarized the development of kinetic resolution and desymmetrization of amines through nonenzymatic asymmetric catalytic approaches in the last two decades.1 Introduction2 Kinetic Resolution of Amines2.1 Kinetic Resolution of Amines via Asymmetric Transformations of the Amino Group2.1.1 Asymmetric N-Acylations2.1.2 Asymmetric N-Alkylation2.1.3 Asymmetric N-Arylation2.1.4 Other Asymmetric N-Functionalizations2.1.5 Asymmetric Dehydrogenation of Amines2.1.6 Selective C–N Bond Cleavage of Amines2.2 Kinetic Resolution of Amines via Asymmetric Transformations without Amino Group Participating3 Enantioselective Desymmetrization of Amines3.1 Desymmetrization of Diamines3.2 Desymmetrization of Prochiral Monoamines4 Conclusion and Outlooks
      Citation: Synlett ; : -
      PubDate: 2022-03-07T00:00:00+0100
      DOI: 10.1055/a-1790-3230
       
  • Phosphorus(III)-Promoted 1,2-Boronate Migration and Application to
           Stereoselective gem-C,B-Glycosylation

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      Authors: He; Zhi-Tao
      Abstract: Modifications of glycosidic linkers are valuable in medicinal chemistry and natural-product synthesis. Whereas considerable attention has been paid to the development of methods for monoglycosylation, the corresponding geminal diglycosylation has almost been ignored. Little work has focused on exploring new routes for stereoselective gem-diglycosylation, presumably due to challenges in controlling selectivity and activity on a confined quaternary carbon center. Highlighted herein is a recent advance in stereoselective C,B-glycosylation through an unprecedented PPh3-promoted 1,2-boronate-migration process.
      Citation: Synlett ; : -
      PubDate: 2022-03-03T00:00:00+0100
      DOI: 10.1055/a-1787-1429
       
  • Using Restricted Bond Rotations to Enforce Excited-State Behavior of
           Organic Molecules

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      Authors: Kandappa; Sunil Kumar, Ahuja, Sapna, Singathi, Ravichandranath, Valloli, Lakshmy Kannadi, Baburaj, Sruthy, Parthiban, Jayachandran, Sivaguru, Jayaraman
      Abstract: This account highlights the role of restricted bond rotations in influencing the excited-state reactivity of organic molecules. It highlights the photochemical reactivity of various organic molecules and the design strategies that could be exploited by chemists to utilize restricted bond rotations to uncover new excited-state reactivity and to achieve selectivity.1 Introduction.2 NEER-Principle and Restricted Bond Rotations in the Excited State3 [2+2]-Photocycloaddition of Enamides4 [3+2]-Photocycloaddition vs. Paternò–Büchi Reaction of Enamides5 Divergent Photoreactivity of Enones Dictated by Restricted Bond Rotations: Norrish–Yang reactions vs. 6π-Photocyclization6 Divergent Photoreactivity of Imides with Alkenes: [2+2]-Photocycloaddition vs. Photoene Reaction7 Summary and Outlook
      Citation: Synlett ; : -
      PubDate: 2022-03-02T00:00:00+0100
      DOI: 10.1055/a-1785-6910
       
  • Copper-Mediated C–O/C–N Bond Formation: A Facile Synthesis of
           3-Amidocoumarin, 3-Amidoazacoumarin, and N-Aroylindole ­Derivatives

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      Authors: Worayuthakarn; Rattana, Suddee, Nattanit, Nealmongkol, Prattya, Ruchirawat, Somsak, Thasana, Nopporn
      Abstract: Three different heterocyclic systems (3-amidocoumarins, 3-amidoazacoumarins, and N-benzoylindol-2-carboxamides) were synthesized based on the strikingly different selectivity of copper-mediated C–O/C–N bond formation from azlactones under various heating conditions. The stereochemistry of the double bond dictated the nature of the products. Microwave irradiation played an important role in the isomerization of the trisubstituted olefin leading to the formation of 3-amidocoumarins and 3-amidoazacoumarins. Three products showed promising-to-good cytotoxic activities against a panel of cancer cell lines, including HepG2 (hepatoblastoma) and MOLT-3 (T-lymphoblast acute lymphoblastic leukemia).
      Citation: Synlett ; : -
      PubDate: 2022-03-01T00:00:00+0100
      DOI: 10.1055/a-1784-1973
       
  • Cyclization of o-Alkynylisocyanobenzenes with 1,3-Dicarbonyl Compounds

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      Authors: La-ongthong; Kannika, Sawekteeratana, Natthapat, Klaysuk, Jasarin, Soorukram, Darunee, Leowanawat, Pawaret, Reutrakul, Vichai, Krobthong, Sucheewin, Wongtrakoongate, Patompon, Kuhakarn, Chutima
      Abstract: A facile and convenient reaction of o-alkynylisocyanobenzenes with various active-methylene compounds, including 1,3-diesters, 1,3-diketones, β-keto esters, and β-keto amides, under Brønsted basic conditions, has been developed. Diethyl malonate reacted smoothly with a collection of o-alkynylisocyanobenzenes to provide the corresponding 2-quinolin-2-yl malonates in excellent yields. Acetylacetone gave a mixture of quinolin-4-yl and quinolin-2-yl derivatives. Acetoacetate esters and acetoacetyl amide derivative initially gave 2-quinolin-2-yl adducts that underwent partial deacetylation under the reaction conditions.
      Citation: Synlett ; : -
      PubDate: 2022-03-01T00:00:00+0100
      DOI: 10.1055/a-1784-2513
       
  • Dimerization of 3-Chlorooxindoles Mediated by Potassium
           Ethyl­xanthate: Synthesis of Isoindigos

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      Authors: Meesin; Jatuporn, Chotsaeng, Nawasit, Kuhakarn, Chutima
      Abstract: A novel dimerization of 3-chlorooxindoles promoted by potassium ethylxanthate to access isoindigo derivatives is described. The reactions proceeded readily at room temperature in short reaction times. A mechanistic study revealed that the 3-chlorooxindole is initially converted into O-ethyl S-(2-oxo-2,3-dihydro-1H-indol-3-yl) dithiocarbonate, which subsequently undergoes dimerization with elimination of carbon disulfide. In almost all cases, analytically pure isoindigos were isolated in moderate to good yields without a requirement for chromatographic purification.
      Citation: Synlett ; : -
      PubDate: 2022-03-01T00:00:00+0100
      DOI: 10.1055/a-1784-2304
       
  • 4b-Aryltetrahydroindeno[1,2-a]indenes by Acid-Catalyzed Trans­annular
           Cyclization of Benzannulated Cyclooctene Alcohols

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      Authors: Songthammawat; Poramate, Phumjan, Tanawat, Ruchirawat, Somsak, Ploypradith, Poonsakdi
      Abstract: By starting from two simple building blocks, benzannulated cyclooctenones were obtained in three steps. Subsequent Grignard/aryl lithium addition to the ketone yielded the corresponding tertiary alcohols that underwent stereoselective acid-catalyzed transannular cyclization to provide a cis-fused 5/5 bicyclic indanylindane framework exclusively. Subsequent stereoselective nucleophilic addition to the indanyl cation by hydride, water, or electron-rich aromatics furnished the 4b-aryltetrahydroindano[1,2-a]indenes in good to excellent yields (up to 92%) in the trans-C9–C9a form in up to a>99:1 diastereomeric ratio.
      Citation: Synlett ; : -
      PubDate: 2022-02-22T00:00:00+0100
      DOI: 10.1055/a-1778-8143
       
  • Complementary Photocatalytic Toolbox: Control of Intramolecular endo-
           versus exo-trig Cyclizations of α-Phenyl Olefins to Oxaheterocyclic
           Products

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      Authors: Weick; Fabian, Steuernagel, Desirée, Belov, Arina, Wagenknecht, Hans-Achim
      Abstract: The regioselectivity of the intramolecular cyclization of bifunctional α-phenyl alkenes can be controlled simply by the choice of the organic chromophore as the photocatalyst. The central photoredox catalytic reaction in both cases is a nucleophilic addition of the hydroxy function to the olefin function of the substrates. N,N-(4-Diisobutylaminophenyl)phenothiazine catalyzes exo-trig cyclizations, whereas 1,7-dicyanoperylene-3,4,9,10-tetracarboxylic acid bisimides catalyze endo-trig additions to products with anti-Markovnikov regioselectivity. We preliminarily report the photoredox catalytic conversions of 11 representative substrates into 20 oxaheterocycles in order to demonstrate the similarity, but also the complementarity, of these two variants in this photoredox catalytic toolbox.
      Citation: Synlett ; : -
      PubDate: 2022-02-18T00:00:00+0100
      DOI: 10.1055/s-0040-1719871
       
  • Chiral Polyoxygenated Tertiary Alcohols Through Kiyooka Aldol Reaction

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      Authors: Kalesse; Markus, Lücke, Daniel
      Abstract: Here we present our work on a Kiyooka aldol protocol for the stereoselective synthesis of tertiary alcohols. In the obtained products, three oxygenated carbon atoms that could further be differentiated flank the chiral tertiary alcohol. This methodology can be applied to simple aromatic or aliphatic aldehydes and more complex substrates bearing a chiral center in the α and/or β-position. For complex substrates, an unexpected dependency between stereoselectivity and double bond geometry of the ketene acetal was observed. Furthermore, applications in or towards the synthesis of natural products are presented. 1 Introduction2 Scope of the reaction 3 Synthetic applications 4 Conclusion
      Citation: Synlett ; : -
      PubDate: 2022-02-17T00:00:00+0100
      DOI: 10.1055/a-1775-7590
       
  • Dihalooxygenation of Alkynes and Alkynols: Preparation of
           2,2-Dihaloketones and gem-Dihalolactols

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      Authors: Chaisan; Nattawadee, Ruengsangtongkul, Sureeporn, Thongsornkleeb, Charnsak, Tummatorn, Jumreang, Ruchirawat, Somsak
      Abstract: A mild and convenient method for the synthesis of 2,2-dihaloketones and gem-dihalolactols has been developed. For the synthesis of 2,2-dihaloketones, alkynes were employed as substrates to react with halogenating agents, Cl2 or ClBr, that were generated in situ from aqueous HCl and NCS or NBS, respectively. On the other hand, gem-dihalolactols could be prepared from alkynol substrates by using the same reaction conditions. This method could be applied to a broad range of substrates to give the corresponding products in low to good yields.
      Citation: Synlett ; : -
      PubDate: 2022-02-17T00:00:00+0100
      DOI: 10.1055/a-1774-7077
       
  • Ceric Ammonium Nitrate Promoted Oxidative Coupling of Terminal Alkynes and
           1,3-Keto Esters: A Synthesis of Unsymmetrical 1,1,2-Triacylalkenes

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      Authors: Ruengsangtongkul; Sureeporn, Kuribara, Takahito, Chaisan, Nattawadee, Tummatorn, Jumreang, Thongsornkleeb, Charnsak, Ruchirawat, Somsak
      Abstract: Unsymmetrical 1,1,2-triacylalkenes were conveniently prepared by the oxidative coupling of 1,3-keto esters with terminal alkynes by employing 4.0 equivalents of inexpensive ceric ammonium nitrate (CAN) as the oxidant in acetonitrile as the solvent at 0 °C. The method is milder than previously reported methods and can be conducted under air, thereby demonstrating its practicality and versatility for preparing these useful building blocks. The reaction is believed to occur by a single-electron-transfer process of the 1,3-keto ester substrate initiated by CAN to generate an α-radical species that quickly adds to the terminal alkyne partner in the reaction. Subsequent oxidation of the resulting vinyl radical by air and CAN then leads to the formation of the triacylalkene product as a mixture of E- and Z-isomers. The reaction was shown to be general, with 27 illustrative examples of the formation of the desired products in up to quantitative yield and with moderate to excellent alkene geometrical selectivities.
      Citation: Synlett ; : -
      PubDate: 2022-02-17T00:00:00+0100
      DOI: 10.1055/a-1774-6966
       
  • Chrysene-Cored Fluorescent Dendrimers as Nondoped Deep-Blue Emitters for
           Solution-Processable Electroluminescent Devices

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      Authors: Chatsirisupachai; Jirat, Sudyoadsuk, Taweesak, Namuangrak, Supawadee, Promarak, Vinich
      Abstract: New solution-processable chrysene-basked deep-blue fluorescent dendrimers consisting of chrysene as a core end-capped by carbazole dendrons were designed, synthesized, and characterized. These dendrimers exhibit strong deep-blue emissions in solution or thin-film states with decent hole mobility and high thermal and electrochemical stability. They can be effectively used as nondoped emitters in organic light-emitting diodes (OLEDs). The nondoped OLEDs, which have a simple structure, showed good electroluminescence (EL) performance (luminance: 2334–2400 cd m–2; external quantum efficiency: 1.88-2.51%; turn-on voltage: 3.8–4.0 V) and deep-blue EL spectra (CIE y: 0.065–0.075) with a narrow full width at half maximum of 61–65 nm.
      Citation: Synlett ; : -
      PubDate: 2022-02-15T00:00:00+0100
      DOI: 10.1055/a-1771-9389
       
  • Direct Synthesis of N-Monosubstituted Benzimidazol-2-ones via
           Ph3P–I2-Mediated Reaction of Hydroxamic Acids

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      Authors: Wiriya; Nittaya, Yamano, Dolnapa, Hongsibsong, Surat, Pattarawarapan, Mookda, Phakhodee, Wong
      Abstract: A facile approach for the synthesis of benzimidazolones via a Ph3P–I2 promoted reaction of hydroxamic acids is reported. Upon Lossen-type rearrangement of the O-activated hydroxamic acids, the in situ generated isocyanates undergo an intramolecular attack by ortho N-nucleophiles producing the cyclized products in good yields under mild conditions. The method allows the direct preparation of a single regioisomer of N-monosubstituted derivatives using readily accessible starting materials and low-cost reagents with broad substrate scope.
      Citation: Synlett ; : -
      PubDate: 2022-02-14T00:00:00+0100
      DOI: 10.1055/s-0040-1719897
       
  • Palladium-Catalyzed Coupling of Biphenyl-2-yl Trifluoromethanesulfonates
           with Dibromomethane to Access Fluorenes

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      Authors: Pan; Shulei, Zhu, Qiongqiong, Zhang, Yanghui
      Abstract: A facile and efficient method has been developed for the synthesis of fluorenes by Pd-catalyzed C–H alkylation of biphenyl-2-yl trifluoromethanesulfonates. The trifluoromethanesulfonates are more readily available and more environmentally benign than biphenyl iodides, and are advantageous substrates for traceless directing-group-assisted C–H activation. The reaction generates C,C-palladacycles as the key intermediates that form two C(sp2)–C(sp3) bonds through reaction with CH2Br2. The reaction tolerates various functional groups, permitting easy access to a range of fluorene derivatives.
      Citation: Synlett ; : -
      PubDate: 2022-02-11T00:00:00+0100
      DOI: 10.1055/a-1770-1078
       
  • Asymmetric Formal Synthesis of (–)-Swainsonine from Chiral-Pool
           Precursors d-Mannose and d-Arabinose

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      Authors: Lamor; Anphisa, Uipanit, Suwanan, Yakhampom, Sujitra, Ngernmeesri, Paiboon, Kongkathip, Ngampong, Kongkathip, Boonsong, Chuanopparat, Nutthawat
      Abstract: Carbohydrates have played an important role in organic synthesis. Since they contain many stereocenters, they have been widely used as chiral-pool starting materials. Herein, we report the asymmetric formal synthesis of (–)-swainsonine, which exhibits anticancer and immunosuppressive activities and inhibits lysosomal α-mannosidase activity, from d-mannose and d-arabinose. The synthesis utilized Zn-mediated Bernet–Vasella reaction, Horner–Wadsworth–Emmons olefination, and Grubbs olefin metathesis as key reactions.
      Citation: Synlett ; : -
      PubDate: 2022-02-04T00:00:00+0100
      DOI: 10.1055/s-0041-1737335
       
  • A Photoenzyme for Challenging Lactam Radical Cyclizations

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      Authors: Nicholls; Bryce T., Qiao, Tianzhang, Hyster, Todd K.
      Abstract: Reductive radical cyclizations are ubiquitous in organic synthesis and have been applied to the synthesis of structurally complex molecules. N-Heterocyclic motifs can be prepared through the cyclization of α-haloamides; however, slow rotation around the amide C–N bond results in preferential formation of an acyclic hydrodehalogenated product. Here, we compare four different methods for preparing γ-, δ-, ε-, and ζ-lactams via radical cyclization. We found that a photoenzymatic method using flavin-dependent ‘ene’ reductases affords the highest level of product selectivity. We suggest that through selective binding of the cis-amide isomer, the enzyme preorganizes the substrate for cyclization, helping to avoid premature radical termination.
      Citation: Synlett ; : -
      PubDate: 2022-01-28T00:00:00+0100
      DOI: 10.1055/s-0040-1719872
       
  • Electrostatically Directed meta-Selective Borylation of Arenes

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      Authors: Chaturvedi; Jagriti, Haldar, Chabush, Chattopadhyay, Buddhadeb
      Abstract: The constitutional challenge of an electrostatically directed meta borylation of sterically biased and unbiased substrates is summarized in the present work. The borylation follows an electrostatic interaction between the partially positive and negative charges of the ligand and substrate, respectively. Using our developed strategy, it has been demonstrated that a wide range of challenging substrates, especially 4-substituted substrates can be borylated at the meta position with excellent selectivity. Moreover, unsubstituted substrates are also displayed excellent meta selectivity. The reaction employs bench-stable ligand, proceeds at moderate reaction temperature (40–80 °C), precluding the need to synthesize bulky and sophisticated ligand/template.
      Citation: Synlett ; : -
      PubDate: 2022-01-18T00:00:00+0100
      DOI: 10.1055/a-1743-4650
       
  • Mechanochemical Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazoles Mediated
           by PPh3-TCCA

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      Authors: Yamano; Dolnapa, Wiriya, Nittaya, Phakhodee, Wong, Wet-osot, Sirawit, Pattarawarapan, Mookda
      Abstract: Mechanochemical synthesis of 2,5-disubstituted 1,3,4-oxadiazoles was developed as an environmentally benign alternative to conventional solvent-based methods. In the presence of triphenylphosphine and trichloroisocyanuric acid, N-acylbenzotriazoles condense with acylhydrazides leading to oxadiazoles derivatives in good to excellent yields within minutes. The approach circumvents the need for strictly anhydrous conditions, external heating, long reaction times, as well as tedious multistep procedures. A range of substrates with reactive functionalities was also well tolerated.
      Citation: Synlett ; : -
      PubDate: 2022-01-18T00:00:00+0100
      DOI: 10.1055/s-0040-1719867
       
  • Claisen Rearrangement Triggered by Brønsted Acid Catalyzed Alkyne
           Alkoxylation

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      Authors: Yan; Yao-Hong, Li, Long, Ye, Long-Wu
      Abstract: Over the past two decades, catalytic alkyne alkoxylation-initiated Claisen rearrangement has proven to be a practical and powerful strategy for the rapid assembly of a diverse range of structurally complex molecules. The rapid development of Claisen rearrangements triggered by transition-metal-catalyzed alkyne alkoxylation has shown great potential in the formation of carbon–carbon bonds in an atom-economic and mild way. However, metal-free alkyne alkoxylation-triggered Claisen rearrangement has seldom been exploited. Recently, Brønsted acids such as HNTf2 and HOTf have been shown to be powerful activators that promote catalytic alkyne alkoxylation/Claisen rearrangement, leading to the concise and flexible synthesis of valuable compounds with high efficiency and atom economy. Recent advances on the Brønsted acid catalyzed alkyne alkoxylation/Claisen rearrangement are introduced in this Account, in which both intramolecular and intermolecular tandem reactions are discussed.
      Citation: Synlett ; : -
      PubDate: 2022-01-13T00:00:00+0100
      DOI: 10.1055/s-0040-1719866
       
  • A Highly Durable, Self-Photosensitized Mononuclear Ruthenium Catalyst for
           CO2 Reduction

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      Authors: Kamada; Kenji, Okuwa, Hiroko, Wakabayashi, Taku, Sekizawa, Keita, Sato, Shunsuke, Morikawa, Takeshi, Jung, Jieun, Saito, Susumu
      Abstract: A novel mononuclear ruthenium (Ru) complex bearing a PNNP-type tetradentate ligand is introduced here as a self-photosensitized catalyst for the reduction of carbon dioxide (CO2). When the pre-activation of the Ru complex by reaction with a base was carried out, an induction period of catalyst almost disappeared and the catalyst turnover numbers (TONs) over a reaction time of 144 h reached 307 and 489 for carbon monoxide (CO) and for formic acid (HCO2H), respectively. The complex has a long lifespan as a dual photosensitizer and reduction catalyst, due to the sterically bulky and structurally robust (PNNP)Ru framework. Isotope-labeling experiments under 13CO2 atmosphere indicate that CO and HCO2H were both produced from CO2.
      Citation: Synlett ; : -
      PubDate: 2021-11-29T00:00:00+0100
      DOI: 10.1055/a-1709-0280
       
 
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