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Journal Cover Tetrahedron Letters
  [SJR: 0.782]   [H-I: 145]   [121 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0040-4039 - ISSN (Online) 1359-8562
   Published by Elsevier Homepage  [3089 journals]
  • Synthesis of N-alkoxy-substituted 2H-benzimidazoles
    • Authors: Nurul H. Ansari; Arica L. Jordan; Björn C.G. Söderberg
      Pages: 4811 - 4821
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Nurul H. Ansari, Björn C.G. Söderberg
      Treatment of 2-nitro-N-(2-methyl-1-propen-1-yl)benzenamines with potassium tert-butoxide in tert-butanol followed by the addition of an electrophile affords N-alkoxy-2H-benzimidazoles. Electrophiles including methyl iodide, allylic bromides, propargylic bromides, benzyl bromide, and acetyl chloride gave good to excellent yields of product while 1-iodo- and 2-iodo-butane afforded very low yields.
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      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tet.2017.06.063
       
  • Recent advancements in the synthesis of pentafluorosulfanyl
           (SF5)-containing heteroaromatic compounds
    • Authors: Prajwalita Das; Etsuko Tokunaga; Norio Shibata
      Pages: 4803 - 4815
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Prajwalita Das, Etsuko Tokunaga, Norio Shibata
      The unique features of the pentafluorosulfanyl (SF5) group have made it renowned as a “super trifluoromethyl (CF3)” group. Owing to the big success of CF3-containing heteroaromatic compounds in medicinal chemistry, agro-chemistry and material sciences, SF5-substituted heteroaromatic compounds have gained a lot of attention in very recent years as novel and potential candidates in these fields. However, the synthetic methodology for SF5-substituted heteroaromatic compounds is still highly limited. This digest highlights the recent, rapid, and significant advances made in the synthesis of SF5-heteroaromatics.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.015
       
  • One-pot synthesis of 6H-2,2a1,3-triazaaceanthrylen-6-ones and
           6H-2,2a1,4-triazaaceanthrylen-6-ones via tandem cyclization strategies
    • Authors: Bing Mu; Jingya Li; Dapeng Zou; Yusheng Wu; Junbiao Chang; Yangjie Wu
      Pages: 4816 - 4821
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Bing Mu, Jingya Li, Dapeng Zou, Yusheng Wu, Junbiao Chang, Yangjie Wu
      Two operationally simple one-pot protocols have been developed for the synthesis of 6H-2,2a1,3-triazaaceanthrylen-6-ones and 6H-2,2a1,4-triazaaceanthrylen-6-ones. The first Pd-catalyzed tandem cyclization of imidazo[1,2-a]pyrimidines/imidazo[1,2-a]pyrazines with 2-chlorobenzaldehydes could proceed in aqueous medium under air, affording the desired products in moderate to good yields. The molecular structures of products 3i and 5b were confirmed by X-ray crystallographic analysis.
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      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.09.029
       
  • Synthesis of eight-membered aminocyclitol analogues
    • Authors: Yunus Zozik; Emine Salamci; Ayşe Kilic
      Pages: 4822 - 4826
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Yunus Zozik, Emine Salamci, Ayşe Kilic
      The first syntheses of four stereoisomeric diaminocyclooctane diols, as well as a chlorocyclooctane aminodiol, are reported. In the first part, photooxygenation of cis,cis-1,3-cyclooctadiene gave a bicyclic endoperoxide, which was reduced with zinc followed by mesylation of the hydroxyl groups. Treatment with sodium azide afforded 1,4- and 1,2-cyclooctene diazides. Oxidation of the double bonds in the isomeric diazides with OsO4, followed by hydrogenation of the azide groups, led to 3,8-diaminocyclooctane-1,2-diol and 3,4-diaminocyclooctane-1,2-diols. In the second part, cis-3,8-diazidocyclooctene was converted into the corresponding epoxide. Stereospecific hydrolysis of the epoxide ring with HCl(g) in methanol, and hydrogenation of the azide groups gave 3,8-diamino-2-chloro-cyclooctan-1-ol. Bromination of the double bond in cyclooctene diacetate, followed by acetate deprotection, azidolysis of the bromides, and hydrogenation of the azide groups resulted in the formation of 2,3-diaminocyclooctane-1,4-diol.
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      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.014
       
  • Lycocasuarines A–C, Lycopodium alkaloids from Lycopodiastrum
           casuarinoides
    • Authors: Lu-Lu Wang; Zhong-Bo Zhou; Xin-Liu Zhu; Fang-Yu Yuan; Tomofumi Miyamoto; Ke Pan
      Pages: 4827 - 4831
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Lu-Lu Wang, Zhong-Bo Zhou, Xin-Liu Zhu, Fang-Yu Yuan, Tomofumi Miyamoto, Ke Pan
      Three lycodine-type Lycopodium alkaloids (1–3) were isolated from Lycopodiastrum casuarinoides. Their structures were elucidated by spectroscopic analysis, single-crystal X-ray crystallography, and computational methods. Compound 1 possesses a rearranged five-membered ring D resulting from C-8/C-15 cleavage and a new C-7/C-15 linkage. Compound 2 is the first Lycopodium alkaloid found to bear an additional carbon (C-17) directly bonded to C-8, which is particularly unusual from a biogenetic point of view. Compounds 1–3 were evaluated for acetylcholinesterase inhibitory activities.
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      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.019
       
  • Palladium-catalyzed cycloisomerisation reaction of 1,6-enyne acetic esters
           to form five-membered nitrogenated heterocyclic conjugated trienes
    • Authors: Ting He; Pin Gao; Shan Fang; Yaling Chi; Yuantao Chen
      Pages: 4832 - 4835
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Ting He, Pin Gao, Shan Fang, Yaling Chi, Yuantao Chen
      A palladium-catalyzed cycloisomerisation reaction of 1,6-enyne acetic esters have been developed. This cyclization reaction shows excellent regioselectivity and good functional group tolerance to obtain five-membered nitrogenated heterocyclic conjugated trienes in moderate to excellent yields. The resulting conjugated trienes could be facilely converted to highly substituted benzenes through Diels-Alder reactions.
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      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.018
       
  • FeCl3·6H2O catalyzed diastereoselective synthesis of (L)-menthyl
           4-oxo-2-arylpiperidine-3-carboxylates
    • Authors: Lakshmi V.R. Babu Syamala; Ramakrishna G. Bhat
      Pages: 4836 - 4840
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Lakshmi V.R. Babu Syamala, Ramakrishna G. Bhat
      An efficient diastereoselective synthesis of substituted piperidines is accomplished by using catalytic amount of FeCl3·6H2O via intramolecular aza-Michael addition of carbamate on alkylidene β-keto (L)-menthyl esters in a very short time.
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      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.026
       
  • New pyrrolo[3,2-b]pyrrole derivatives with multiple-acceptor substitution:
           Efficient fluorescent emission and near-infrared two-photon absorption
    • Authors: Huan Liu; Jun Ye; Yu Zhou; Lulu Fu; Qinghua Lu; Chi Zhang
      Pages: 4841 - 4844
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Huan Liu, Jun Ye, Yu Zhou, Lulu Fu, Qinghua Lu, Chi Zhang
      Two new D-π-A organic chromophores, 1,2,4,5-tetra(4-cyanophenyl)pyrrolo[3,2-b]pyrrole (4CNPP) and 1,2,3,4,5,6-hexa(4-cyanophenyl)pyrrolo[3,2-b]pyrrole (6CNPP), were developed by modifying the electron-rich pyrrolo[3,2-b]pyrrole (PP) unit with four and six 4-cyanophenyls respectively. The compounds exhibited bright blue emissions in low- to high-polarity solvents, with high Фfs of 88–90% in toluene, as well as impressive two-photon absorption cross-sections at the near-infrared (NIR) 700 nm.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.028
       
  • Catalyst-free, efficient and one pot protocol for synthesis of nitriles
           from aldehydes using glycerol as green solvent
    • Authors: Ajit P. Ingale; Shripad M. Patil; Sandeep V. Shinde
      Pages: 4845 - 4848
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Ajit P. Ingale, Shripad M. Patil, Sandeep V. Shinde
      We described herein the novel, efficient and one-pot catalyst free protocol for the synthesis of nitriles from aldehydes by using hydroxyl amine hydrochlorides in glycerol as a green solvent. This protocol was efficiently used for transformation of aromatic aldehydes bearing electron-withdrawing and electron-donating groups into a aryl nitriles in good to excellent yields. The methodology offers a very simple, efficient and environmentally benign procedure.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.032
       
  • New Biosilified Pd-lipase hybrid biocatalysts for dynamic resolution of
           amines
    • Authors: Stefânia P. de Souza; Raquel A.C. Leão; Jonathan F. Bassut; Ivana C.R. Leal; Shuai Wang; Qiqi Ding; Yingying Li; Frank Leung-Yuk Lam; Rodrigo O.M.A. de Souza; Ivaldo Itabaiana Jr
      Pages: 4849 - 4854
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Stefânia P. de Souza, Raquel A.C. Leão, Jonathan F. Bassut, Ivana C.R. Leal, Shuai Wang, Qiqi Ding, Yingying Li, Frank Leung-Yuk Lam, Rodrigo O.M.A. de Souza, Ivaldo Itabaiana Jr
      In this work lipase CaLB was immobilized on functionalized Pd-SiO2 nanoparticles in order to simplify the DKR of α-methylbenzylamine. Hybrid biocatalysts showed immobilization efficiencies of 82%, 80% and 76% when containing 1, 5 and 10% of Pd respectively. On DKR reaction values of ee > 99% and conversion of 82% were found with only 1% of Pd, generating a productivity of 2.21 mg of product h−1 mg of support−1 against 0.76 found by N435®. Compared to commercial N435®, the novel biocatalysts showed protein loads about 15-fold lower and higher activity, demonstrating competitive performances and high industrial applications.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.031
       
  • CuI catalyzed sulfamidation of arylboronic acid using TsNBr2 at room
           temperature
    • Authors: Dineshwori Chanu Loukrakpam; Prodeep Phukan
      Pages: 4855 - 4858
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Dineshwori Chanu Loukrakpam, Prodeep Phukan
      An expeditious protocol for amidation arylboronic acid has been developed using TsNBr2 as the nitrogen source in presence of a CuI as catalyst. Various arylboronic acids could be transformed into corresponding N-arylsulfonamide derivatives within a very short time using CuI as catalyst in presence of DBU at room temperature.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.033
       
  • Copper-catalyzed remote CH ethoxycarbonyldifluoromethylation of
           8-aminoquinolines with bis(pinacolato)diboron as reductant
    • Authors: Shuaijun Han; Apeng Liang; Xiaoxiao Ren; Xianying Gao; Jingya Li; Dapeng Zou; Yangjie Wu; Yusheng Wu
      Pages: 4859 - 4863
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Shuaijun Han, Apeng Liang, Xiaoxiao Ren, Xianying Gao, Jingya Li, Dapeng Zou, Yangjie Wu, Yusheng Wu
      A simple protocol for the copper/B2pin2-catalyzed CH ethoxycarbonyldifluoromethylation of 8-aminoquinoline scaffolds with functionalized difluoromethyl bromides and iodines was developed, affording the desired products in moderate to good yields. This reaction was carried out under mild conditions and features good substrate tolerance.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.037
       
  • A Tamao–Fleming oxidation route to dipeptides bearing N,O-acetal
           functionality
    • Authors: Sherif M.S. Ibrahim; Koushik Banerjee; Kara A. Slater; Gregory K. Friestad
      Pages: 4864 - 4866
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Sherif M.S. Ibrahim, Koushik Banerjee, Kara A. Slater, Gregory K. Friestad
      Tamao–Fleming oxidation of the N-dimethylphenylsilylmethyl group linked to the nitrogen of a peptide bond enables access to dipeptide N,O-acetal functionality. The N-silylmethyl functionality serves as a latent form of the N,O-acetal which is revealed after peptide bond construction.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.036
       
  • Sulfated liposaccharides inspired by telomerase inhibitor axinelloside A
    • Authors: Jie Guang; Zachary A. Rumlow; Lauren M. Wiles; Sloane O'Neill; Maciej A. Walczak
      Pages: 4867 - 4871
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Jie Guang, Zachary A. Rumlow, Lauren M. Wiles, Sloane O'Neill, Maciej A. Walczak
      Sulfated liposaccharides are known inhibitors of telomerase and here we describe the synthesis of a series of sulfated liposaccharides inspired by the natural product axinelloside A, reported to act as an inhibitor of human telomerase. We established a robust and scalable synthetic route to galactosyl liposaccharides capitalizing on a series of regioselective acylation reactions with 2-decenoic acid and imidazolium sulfate esters.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.038
       
  • Synthesis of 2-substituted 4,5-dihydro-4-oxo-3-furancarboxylates using
           acylative intramolecular cyclization of sulfonium salts
    • Authors: Sho Inagaki; Akari Sato; Haruka Sato; Satoru Tamura; Tomikazu Kawano
      Pages: 4872 - 4875
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Sho Inagaki, Akari Sato, Haruka Sato, Satoru Tamura, Tomikazu Kawano
      A simple and efficient synthesis of 4,5-dihydro-4-oxo-3-furancarboxylates using an acylative intramolecular cyclization of sulfonium salts is described. The reaction involved the efficient formation of a mixed anhydride between a linear carboxylic acid and trifluoroacetic anhydride in the presence of N-methylimidazole, followed by the sequential conversion into a highly reactive acylammonium species in situ. This procedure is easily handled, uses readily available inexpensive reagents, and provides a variety of 2-substituted 4,5-dihydro-4-oxo-3-furancarboxylates.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.035
       
  • Progress on PPAPs cyclization: Guttiferone A as a case study
    • Authors: Pauline Menelle; Kévin Cottet; Yann Fromentin; Thomas Gaslonde; François-Hugues Porée; Didier Buisson; Marie-Christine Lallemand
      Pages: 4876 - 4879
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Pauline Menelle, Kévin Cottet, Yann Fromentin, Thomas Gaslonde, François-Hugues Porée, Didier Buisson, Marie-Christine Lallemand
      Guttiferone A and cyclized analogs are naturally occurring polycyclic polyprenylated acyl phloroglucinols possessing antiparasitic activities. Naturally occurring xanthones possess increased activity, but are either rare or difficult to synthesize. In this paper, three optimized methodologies to access natural, hydroxylated and non-natural xanthonic skeletons from guttiferone A are described. These compounds will serve as starting materials for further SAR studies.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.041
       
  • Heterogeneous borrowing hydrogen reactions with Pd/C and ZnO: Diol scope
    • Authors: Pedro J. Llabres-Campaner; Patricia Woodbridge-Ortega; Rafael Ballesteros-Garrido; Rafael Ballesteros; Belén Abarca
      Pages: 4880 - 4882
      Abstract: Publication date: 27 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 52
      Author(s): Pedro J. Llabres-Campaner, Patricia Woodbridge-Ortega, Rafael Ballesteros-Garrido, Rafael Ballesteros, Belén Abarca
      A borrowing hydrogen reaction with different diols was employed for the preparation of complex beta- gamma- or epsilon-amino alcohols from p-toluidine and tetrahydroquinoline with the aim of better understanding the applicability of the Pd/C ZnO heterogeneous catalyst.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.039
       
  • Recent topics in the desymmetrization of meso-diols
    • Authors: Takeyuki Suzuki
      Pages: 4731 - 4739
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Takeyuki Suzuki
      The desymmetrization of meso compounds is one of the most effective strategies for asymmetric synthesis. This digest focuses on recent progress in the desymmetrization of meso-diols and their derivatives. The topics discussed here include methods for the enzymatic acylation of meso-diols and the hydrolysis of meso-diesters, acylation, related reactions of meso-diols with organocatalysts and metal catalysts, the oxidation of meso-diols by enzymes, organocatalysts, and metal catalysts, and the desymmetrization of meso-dicarbamates with metal catalysts. The desymmetrization of meso-diols using tandem reactions is also discussed.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.048
       
  • Silver-catalyzed efficient synthesis of enaminones from propargyl alcohols
           and amines
    • Authors: Mengshun Li; Dongmei Fang; Feng Geng; Xianping Dai
      Pages: 4747 - 4749
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Mengshun Li, Dongmei Fang, Feng Geng, Xianping Dai
      Enaminones are used as the key intermediates to construct heterocyclic compounds with various bioactivities. In this study, a simple and efficient approach for the synthesis of enaminones via amination of propargyl alcohols was developed. Under the catalysis of Ag2CO3, the reaction proceeded smoothly to afford the desired products in good yields. Preliminary mechanism experiments showed that Ag2CO3 played an essential role in the procedure of the reaction.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.09.054
       
  • NH insertion reactions catalyzed by reusable water-soluble
           ruthenium(II)-hm-phenyloxazoline complex
    • Authors: Abdel-Moneim Abu-Elfotoh
      Pages: 4750 - 4754
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Abdel-Moneim Abu-Elfotoh
      A water-soluble Ru(II)-hm-pheox complex was efficiently catalyzed NH insertion of EDA with a broad class of amine derivatives in water/ether biphasic medium to deliver the biologically active precursors α-aminoester products with excellent yields (up to >99%). The products were separated by decantation and the catalyst was washed and reused several times (at least 8 times) without any specific loss of its catalytic activity. The plausible mechanism of the reaction was explained. Additionally, In case of ethylene diamine, the NH insertion product could be transformed to biological active piperazinone compound in high yield. The asymmetric version of this catalytic reaction is under investigation.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.062
       
  • Organocatalytic intermolecular [2+2] cycloaddition of norbornadienes by a
           stable organic radical compound
    • Authors: Shuji Kyokane; Yusuke Tanaka; Yoshihisa Sei; Masashi Shiotsuki
      Pages: 4755 - 4758
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Shuji Kyokane, Yusuke Tanaka, Yoshihisa Sei, Masashi Shiotsuki
      An organocatalytic [2+2] cycloaddition reaction of norbornadienes (NBDs) using catalytic amount of TEMPO was reported. Single crystal X-ray diffraction of the product revealed its detailed multicyclic structure containing a 4-membered ring, formed in intermolecular reaction. Addition of AIBN to the current catalytic system improved the product yield. Quantitative reaction of the NBD and TEMPO gave a 2:2 adduct of NBD and TEMPO, which was confirmed by HR-MS. This catalytic [2+2] addition of NBDs has great advantage in selective intermolecular coupling in comparison with [2+2] photocycloaddition.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.072
       
  • Asymmetric conjugate addition of 5-benzylfurfurals to nitroalkenes using a
           diaminomethylenemalononitrile organocatalyst
    • Authors: Hiroshi Akutsu; Kosuke Nakashima; Shin-ichi Hirashima; Moeko Kitahara; Yuji Koseki; Tsuyoshi Miura
      Pages: 4759 - 4762
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Hiroshi Akutsu, Kosuke Nakashima, Shin-ichi Hirashima, Moeko Kitahara, Yuji Koseki, Tsuyoshi Miura
      A pyrrolidine–diaminomethylenemalononitrile organocatalyst efficiently promotes the asymmetric direct bisvinylogous Michael addition of 5-benzylfurfural derivatives to nitroalkenes, affording the corresponding ε-regioselective addition products in high yields with up to 86% ee.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.078
       
  • Silver-catalyzed decarboxylative cross-coupling of α-keto acids with
           alkenes giving approach to chalcones
    • Authors: Shang Wu; Hongheng Yu; Qinzheng Hu; Quanlu Yang; Shouwang Xu; Tian Liu
      Pages: 4763 - 4765
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Shang Wu, Hongheng Yu, Qinzheng Hu, Quanlu Yang, Shouwang Xu, Tian Liu
      A silver-catalyzed decarboxylative cross-coupling of α-keto acids with alkenes is reported. The method, with a wide range of substrate tolerance and mild operational conditions, can produce various chalcone derivatives in moderate to high yields from easily available starting materials.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.005
       
  • A re-investigation of the Fries rearrangement of 3-chlorophenyl acetate
           and synthesis of 2-azido-1-(4-(benzyloxy)-2-chlorophenyl)ethanone from
           4-bromo-3-chlorophenol
    • Authors: Panayiotis A. Procopiou; Diane M. Coe; George Procopiou
      Pages: 4766 - 4768
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Panayiotis A. Procopiou, Diane M. Coe, George Procopiou
      The Fries rearrangement of 3-chlorophenyl acetate provided the expected 4-chloro-2-hydroxy-acetophenone as the major product and 2,4-diacetyl resorcinol and 2-chloro-4-hydroxy-acetophenone as minor products. 4-Benzyloxy-2-chloroacetophenone was prepared by a Heck reaction and then elaborated to 4-benzyloxy-2-chlorophenacyl azide.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.016
       
  • Two highly selective fluorescence probes for imaging Pd2+ in cells and
           mice
    • Authors: Mei-Pan Yang; Bing-Qin Yang; Long-Li Kang; Li Wang; Li-Feng Ma; Jing Li; Yuan Zhang
      Pages: 4769 - 4775
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Mei-Pan Yang, Bing-Qin Yang, Long-Li Kang, Li Wang, Li-Feng Ma, Jing Li, Yuan Zhang
      Two rhodamine-based probes were designed and prepared, which exhibited highly sensitive and selective fluorescence enhancement upon binding to Pd2+ by UV–vis and fluorescence spectroscopies. Meanwhile the distinct color changes and rapid switch-on fluorescence also provided “naked-eyes” detection for Pd2+ over a broad pH range. The recognition mechanism was explored through Job’s plot, MS data, IR spectra and related theoretical calculations. Furthermore, the probes were applied for biological imaging to confirm that they can be used for monitoring Pd2+ in living cells (L929 and A549 cells) and living mice with satisfying results, which further demonstrated their value of practical applications in environmental and biological systems.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.017
       
  • Enamines of 3-acyltetramic acids from β-enamino amides and amino
           acids
    • Authors: Plamen Angelov; Silvia Ivanova; Pavel Yanev
      Pages: 4776 - 4778
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Plamen Angelov, Silvia Ivanova, Pavel Yanev
      A novel approach for the synthesis of enamine derivatives of N-protected 3-acyltetramic acids is described. The synthetic procedure relies on α-C-acylation of β-enamino amides with N-protected α-amino acids and subsequent cyclisation of the obtained intermediates in refluxing TFA. The tetramic derivatives are obtained with very good enantiopurity (e.r. ≥95:5). Ring-enlarged analogues (piperidine-2,4-diones) can also be obtained from β-amino acids.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.023
       
  • Concise synthesis of the bioactive natural polyhydroxynaphthoate
           parvinaphthol B via Hauser-Kraus annulation
    • Authors: Sungwan Ahn; Young Taek Han
      Pages: 4779 - 4780
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Sungwan Ahn, Young Taek Han
      Herein, we describe the first total synthesis of parvinaphthol B, a polyhydroxynaphthoate derived from the root of Pentas parvifolia which exhibits cytotoxic effects against the TNBC cell line. The key feature of the synthesis involves a Hauser-Kraus annulation to provide the polyhydroxynaphthoate skeleton. The synthesis requires only six linear steps and afforded the product in 26.5% overall yield, thus representing a simple method for the further preparation of analogs and biological studies.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.024
       
  • Kinetic resolution of phenyl methyl sulfoxides by mammalian methionine
           sulfoxide reductase A
    • Authors: Cesare Achilli; Annarita Ciana; Giampaolo Minetti
      Pages: 4781 - 4782
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Cesare Achilli, Annarita Ciana, Giampaolo Minetti
      Chiral sulfoxides are widely used in organic synthesis as chiral auxiliaries. There are numerous strategies for the preparation of enantiomerically pure sulfoxides, based either on the enantioselective oxidation of sulphides or the enantiospecific reduction of sulfoxides. For both cases, bioconversion techniques have been developed and proposed for large-scale synthesis. Methionine sulfoxide reductase enzymes (MsrA and MsrB) catalyse the stereoselective conversion of methionine sulfoxide to methionine. MsrA can also catalyse the reduction of other exogenous sulfoxides, including p-tolyl methyl sulfoxide. However, the stereoselectivity towards this type of substrate is not yet well characterized. The activity and enantioselectivity of MsrA toward several aryl methyl sulfoxides is presented in this paper.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.022
       
  • Base-promoted formal [4 + 1+1] annulation of aldehyde, N-benzyl
           amidine and DMSO toward 2,4,6-triaryl pyrimidines
    • Authors: Jin Yuan; Jingbo Li; Bingbing Wang; Song Sun; Jiang Cheng
      Pages: 4783 - 4785
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Jin Yuan, Jingbo Li, Bingbing Wang, Song Sun, Jiang Cheng
      A base-promoted formal [4 + 1+1] annulation of aldehyde, N-benzyl amidine and DMSO was developed, leading to a series of 2,4,6-triaryl pyrimidines in moderate to good yields. Notably, DMSO served as a methine source, which was activated by base rather than either Lewis acid or electrophile. Molecular O2 was the sole eco-friendly oxidant during this procedure.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.020
       
  • The use of 2-hydroxymethyl benzoic acid as an effective water surrogate in
           the Passerini reaction: A straightforward access to α-hydroxyamides
    • Authors: Marta Serafini; Alessia Griglio; Elena Oberto; Tracey Pirali; Gian Cesare Tron
      Pages: 4786 - 4789
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Marta Serafini, Alessia Griglio, Elena Oberto, Tracey Pirali, Gian Cesare Tron
      Dozens of strategies have been described for the synthesis of α-hydroxyamides over the years, but they share common drawbacks in terms of generality and tolerability, especially to acid labile functionalities. Here we report a truncated Passerini reaction suitable for the easy and mild preparation of functionalized α-hydroxyamides. In particular, this procedure is tolerant to acid sensitive protecting groups, which remain intact during the multicomponent reaction.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.021
       
  • Water-acetic acid mediated an efficient and eco-friendly protocol for the
           one-pot synthesis of bis-isoxazolyl amino dihydro-1H-indol-4(5H)-ones
           under mild reaction conditions
    • Authors: Modugu Nagi Reddy; Pittala Praveen Kumar
      Pages: 4790 - 4795
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Modugu Nagi Reddy, Pittala Praveen Kumar
      A cost-effective and eco-friendly straightforward synthesis of new bis-isoxazolyl amino dihydro-1H-indol-4(5H)-ones is successfully achieved via one-pot three-component reaction of N-isoxazolyl enaminone, aryl glyoxal monohydrates and 4-amino-3-methyl-5-styrylisoxazoles by using water as a reaction medium and acetic acid (AcOH) as cheap and green promoter. The protocol proves to be an efficient and environmentally benign in terms of high yields, low reaction time, operational simplicity, metal-free and wide substrates scope. Most important of all, this reaction process is green.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.027
       
  • A short synthesis of 3-enoyltetramic acids employing a new acyl ylide
           conjugate of Meldrum’s acid
    • Authors: Kevin Lovmo; Steffen Dütz; Marina Harras; Robert G. Haase; Wolfgang Milius; Rainer Schobert
      Pages: 4796 - 4798
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Kevin Lovmo, Steffen Dütz, Marina Harras, Robert G. Haase, Wolfgang Milius, Rainer Schobert
      2,2-Dimethyl-5-(triphenylphosphoranylidene)acetyl-1,3-dioxan-4,6-dione (3) is a new activated β-ketoacyl equivalent, readily prepared in quantitative yield by reaction of Meldrum’s acid with the stable ylide Ph3PCCO. Its reaction with α-amino esters affords the corresponding N-(β-ketoacyl)amino ester ylides which, when treated with aldehydes and KOtBu, undergo a simultaneous Wittig olefination cum Dieckmann cyclisation to yield the respective 3-enoyltetramic acids.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.025
       
  • Direct cross-coupling of aryl alkynyliodines with arylsulfinic acids
           leading to alkynyl sulfones under catalyst-free conditions
    • Authors: Leilei Wang; Wei Wei; Daoshan Yang; Huanhuan Cui; Huilan Yue; Hua Wang
      Pages: 4799 - 4802
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Leilei Wang, Wei Wei, Daoshan Yang, Huanhuan Cui, Huilan Yue, Hua Wang
      A facile and efficient one-pot method has been developed for the construction of alkynyl sulfones via direct cross-coupling reaction of aryl alkynyliodines and arylsulfinic acids. The present transformation could be accomplished under catalyst- and additive-free conditions, providing a series of alkynyl sulfones in moderate to good yields with favorable functional group tolerance.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.029
       
  • Recent advances in oxidative C–C coupling reaction of amides with
           carbon nucleophiles
    • Authors: Katsuhiko Moriyama
      Pages: 4655 - 4662
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Katsuhiko Moriyama
      The C–C coupling reaction of N-electron withdrawing group (EWG) protected amides with coupling partners is one of the most important methods for C–C bond formation at the α-position of amides to directly give α-substituted amides. Of the four reactions, namely, the reaction via the generation of carbanion with an electrophile, that via the generation of carbon radical with a radical donor, that via the generation of iminium ion species with a nucleophile (oxidative coupling reaction), and that using a transition metal carbenoid, the oxidative coupling reaction presents a challenge although the reaction products are very useful for the transformation of a wide range of nitrogen-containing derivatives. In this review, recent developments in the oxidative coupling reaction of N-EWG protected amides with nucleophiles are summarized with focus on the reaction using a transition metal, the transition-metal-free reaction, the enantioselective reaction using a chiral catalysts, and the organocatalyzed oxidative coupling reaction.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.081
       
  • Synthesis of new functionalized 3,7-diazabicyclo[3.3.1]nonanes by
           aminomethylation of the Guareschi imides
    • Authors: Anastasiya N. Khrustaleva; Konstantin A. Frolov; Victor V. Dotsenko; Nicolai A. Aksenov; Inna V. Aksenova; Sergey G. Krivokolysko
      Pages: 4663 - 4666
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Anastasiya N. Khrustaleva, Konstantin A. Frolov, Victor V. Dotsenko, Nicolai A. Aksenov, Inna V. Aksenova, Sergey G. Krivokolysko
      The aminomethylation of 4,4-dialkyl-2,6-dioxopiperidine-3,5-dicarbonitriles (Guareschi imides) was studied for the first time. When the Guareschi imides were treated with primary aliphatic amines and an excess of formaldehyde, 2,4-dioxo-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarbonitriles were obtained in varying yields (15–67%). The structure of 9,9-dimethyl-7-(2-methylpropyl)-2,4-dioxo-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarbonitrile was studied by X-ray diffraction analysis.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.069
       
  • Iron-catalyzed CC bond activation/CO bond formation: Direct conversion of
           ketones to esters
    • Authors: Ashot V. Arzumanyan
      Pages: 4667 - 4671
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Ashot V. Arzumanyan
      The iron-catalyzed oxidative activation of the (O)CC bond in ketones has been developed. This method enables direct synthesis of esters by the reaction between ketones and alcohols via conversion of the (O)CC bond to the (O)CO bond. The reaction runs selectively: the (O)CCAlkyl bond is activated, while the (O)CCAryl bond remains intact (i.e., iron-catalyzed intermolecular anti-Baeyer-Villiger activation of the (O)CC bond). The reaction conditions are carefully optimized and allow the production of esters with yields of up to 95%. The method is based on the inexpensive and commercially available catalyst (FeCl3), oxidant ((NH4)2S2O8), and solvent (DCE) without using any ligands or additives.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.068
       
  • Modulating the activity of membrane-active peptides through Zn(II)
           complexation
    • Authors: Pierre-Alexandre Paquet-Côté; Kellie L. Tuck; Jean-Philippe Paradis; Bim Graham; Normand Voyer
      Pages: 4672 - 4676
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Pierre-Alexandre Paquet-Côté, Kellie L. Tuck, Jean-Philippe Paradis, Bim Graham, Normand Voyer
      Seeking to increase the selectivity of antimicrobial peptides for prokaryotic cells, we incorporated a bis-dipicolyl amine (bis-DPA) ligand at the N-terminus of de novo designed model peptides. The Zn2·bisDPA complex increases the interaction of peptides with anionic model membranes, while decreasing interactions with zwitterionic model membranes. Further, it improves the peptides’ antimicrobial activity and decreases their hemolytic activity without substantial changes to their secondary structure. Therefore, incorporating a Zn2·bisDPA complex is a useful strategy to enhance the selectivity of antimicrobial peptides.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.066
       
  • 13C NMR spectroscopic studies of the behaviors of carbonyl compounds in
           various solutions
    • Authors: Yoshikazu Hiraga; Saori Chaki; Satomi Niwayama
      Pages: 4677 - 4681
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Yoshikazu Hiraga, Saori Chaki, Satomi Niwayama
      13C NMR spectroscopic studies were performed for carbonyl compounds having a hydroxyl group, a carboalkoxy group, an acetoxy group, or a carboxyl group in various solvents with different polarities for observation of their behaviors of 13C NMR chemical shifts of carbonyl carbons in solutions. It was found that the chemical shifts of the carbonyl carbons in 13C NMR have good correlation with the empirical parameter for solvent polarities, ET N, depending on the structures. Inter- or intramolecular hydrogen bonding and dipolar-dipolar interactions appear to play a key role in this observation.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.071
       
  • One-pot synthesis of vinylisoxazolidines from simple hydroxylamines and
           conjugated carbonyls
    • Authors: Dylan J. Quinn; Lauren N. Tumbelty; Erica M. Moscarello; Alyson N. Paneque; Amy H. Zinsky; Maxim P. Russ; Graham J. Haun; Nicholas A. Cinti; Ross M. Dare; Gustavo Moura-Letts
      Pages: 4682 - 4686
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Dylan J. Quinn, Lauren N. Tumbelty, Erica M. Moscarello, Alyson N. Paneque, Amy H. Zinsky, Maxim P. Russ, Graham J. Haun, Nicholas A. Cinti, Ross M. Dare, Gustavo Moura-Letts
      Herein is reported the highly chemo- and regioselective synthesis of 3-vinyl-4-formyl and 3-vinyl-5-formylisoxazolidines from enals, hydroxylamines and dipolarophiles under thermal conditions. The reaction works in high yields for a large array of substituted enals and a variety of dipolarophiles. The reaction provides the respective isoxazolidines with high chemoselectivity, stereospecificity and diastereoselectivity without significant purification. The substitution pattern on the dipolarophile directs the regioselectivity of the reaction to provide either 3,4- or 3,5-substituted isoxazolidine isomers. This method provides access to a wide variety of highly substituted, stereochemically dense isoxazolidine scaffolds from the selective reaction of the three proposed components.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.10.076
       
  • Formal synthesis of 14-membered unsymmetrical bis-macrolactone,
           (−)-colletodiol
    • Authors: Navnath B. Khomane; Rayala Naveen Kumar; Prakash R. Mali; Prashishkumar K. Shirsat; H.M. Meshram
      Pages: 4687 - 4690
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Navnath B. Khomane, Rayala Naveen Kumar, Prakash R. Mali, Prashishkumar K. Shirsat, H.M. Meshram
      Formal synthesis of 14-membered unsymmetrical bis-macrolactone, (−)-colletodiol was accomplished from homopropargylic alcohol derivative. Building of the two different hydroxy acid fragments from the same intermediate of homoallylic alcohol was particularly advantageous. A Sharpless asymmetric dihydroxylation, homologation of carbon chain, a Pinnick oxidation, and a macrolactonization to assemble the 14-membered macrodiolide were the additional salient features of this convergent synthesis.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.001
       
  • Mn-MOF@Pi composite: synthesis, characterisation and an efficient catalyst
           for the Knoevenagel condensation reaction
    • Authors: Darsi Rambabu; Mohammad Ashraf; Pooja; Ankush Gupta; Abhimanew Dhir
      Pages: 4691 - 4694
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Darsi Rambabu, Mohammad Ashraf, Pooja, Ankush Gupta, Abhimanew Dhir
      We have synthesised new Mn-MOF@Pi composite by encapsulation of piperidine in desolvated Mn-MOF and investigated its catalytic performance in Knoevenagel condensation reaction. The newly developed composite is compatible with various aromatic aldehydes and converting them to the desired Knoevenagel condensation products in good yields and selectivity. Furthermore, composite Mn-MOF@Pi is reusable and shows good catalytic activity than native MOF.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.004
       
  • Oxoammonium salt-mediated oxidative nitriles synthesis from aldehydes with
           ammonium acetate
    • Authors: Myeong Jin Kim; Junyoung Mun; Jinho Kim
      Pages: 4695 - 4698
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Myeong Jin Kim, Junyoung Mun, Jinho Kim
      An efficient and scalable route for the synthesis of nitriles was developed by oxoammonium salt (4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate) mediated oxidative conversion of aldehydes with NH4OAc. A variety of aliphatic aldehydes as well as benzaldehydes were converted into the corresponding nitriles in high yields. The nitroxyl radical which is the reduced species of the used oxoammonium salt was recovered by simple acid-base extraction for the recycling.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.002
       
  • Synthesis of functionalized 4-nitroanilines by ring transformation of
           dinitropyridone with enaminones
    • Authors: Saki Naito; Soichi Yokoyama; Haruyasu Asahara; Nagatoshi Nishiwaki
      Pages: 4699 - 4702
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Saki Naito, Soichi Yokoyama, Haruyasu Asahara, Nagatoshi Nishiwaki
      2-Functionalized 4-nitroanilines were readily synthesized by ring transformation using 3,5-dinitro-2-pyridone and enaminones prepared from 1,3-dicarbonyl compounds and amines. Modification of the amino group and the ortho-position could be achieved by simply changing the enaminones. Using this strategy, functional groups such as acetyl, benzoyl, and ethoxycarbonyl groups could be introduced into the nitroaniline framework.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.003
       
  • The synthesis of lactone-bridged 1,3,5-triphenylbenzene derivatives as
           pi-expanded coumarin triskelions
    • Authors: Heather A. Hintz; Nicholas J. Sortedahl; Samantha M. Meyer; Daniel A. Decato; Bart J. Dahl
      Pages: 4703 - 4708
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Heather A. Hintz, Nicholas J. Sortedahl, Samantha M. Meyer, Daniel A. Decato, Bart J. Dahl
      Two triply lactone-bridged 1,3,5-triphenylbenzene derivatives with solubilizing moieties have been synthesized in five and six steps from commercially available starting materials. Compounds containing the 1,3,5-triphenylbenzene core with two atom bridges are relatively unknown. This new class of pi-expanded coumarins contain triskelion architectures and X-ray crystallographic studies of one of the triskelions indicates that the 1,3,5-triphenylbenzene core adopts a near-planar geometry. This is the only known example of a two atom-bridged 1,3,5-triphenylbenzene derivative to adopt a planar structure.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.010
       
  • Transition-metal-free synthesis of primary to tertiary carboxamides: A
           quick access to prodrug-pyrazinecarboxamide
    • Authors: Trimbak B. Mete; Ankit Singh; Ramakrishna G. Bhat
      Pages: 4709 - 4712
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Trimbak B. Mete, Ankit Singh, Ramakrishna G. Bhat
      One-pot expedient and direct carbamoylation of heterocyclics is described. The transformation is realized via direct dehydrogenative aminocarbonylation of heterocyclic compounds under transition-metal-free conditions. This method is regioselective and the protocol is proved to be scalable on a gram scale. Further, the therapeutically useful antitubercular agent pyrazinecarboxamide is successfully synthesized by employing this protocol.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.006
       
  • Solvent- and metal-free selective oxidation of thiols to disulfides using
           I2/DMSO catalytic system
    • Authors: Luana Bettanin; Sumbal Saba; Fábio Z. Galetto; Gustavo A. Mike; Jamal Rafique; Antonio L. Braga
      Pages: 4713 - 4716
      Abstract: Publication date: 13 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 50
      Author(s): Luana Bettanin, Sumbal Saba, Fábio Z. Galetto, Gustavo A. Mike, Jamal Rafique, Antonio L. Braga
      We describe herein a simple, fast and inexpensive protocol for the oxidative coupling of thiols employing a stoichiometric amount of DMSO and iodine as the catalyst. Various aromatic disulfides were obtained in good to excellent yields in short reaction times at room temperature, while aliphatic disulfides were achieved in good yields when the reactions were conducted under microwave irradiation.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
      DOI: 10.1016/j.tetlet.2017.11.009
       
  • Asymmetric synthesis of furofurans
    • Authors: Manat Pohmakotr; Chutima Kuhakarn Vichai Reutrakul Darunee Soorukram
      Abstract: Publication date: 20 December 2017
      Source:Tetrahedron Letters, Volume 58, Issue 51
      Author(s): Manat Pohmakotr, Chutima Kuhakarn, Vichai Reutrakul, Darunee Soorukram
      Furofurans are one of the largest sub-types of classical lignans which have been found to possess a broad range of important biological activities. Tremendous efforts have been directed to develop synthetic methodologies for the synthesis of furofurans, especially in a stereoselective manner, due to their interesting bioactivities associated with the structural and stereochemical complexity. This article summarizes the reports on asymmetric synthesis of furofurans disclosed during the period of 2004–2017.
      Graphical abstract image

      PubDate: 2017-12-11T15:37:50Z
       
 
 
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