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Journal Cover
Tetrahedron Letters
Journal Prestige (SJR): 0.683
Citation Impact (citeScore): 2
Number of Followers: 129  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0040-4039 - ISSN (Online) 1359-8562
Published by Elsevier Homepage  [3161 journals]
  • Graphical abstract TOC
    • Abstract: Publication date: 28 February 2019Source: Tetrahedron Letters, Volume 60, Issue 9Author(s):
       
  • Graphical abstract TOC
    • Abstract: Publication date: 28 February 2019Source: Tetrahedron Letters, Volume 60, Issue 9Author(s):
       
  • Graphical abstract TOC contd
    • Abstract: Publication date: 28 February 2019Source: Tetrahedron Letters, Volume 60, Issue 9Author(s):
       
  • Amide bond synthesis via silver(I) N-heterocyclic carbene-catalyzed and
           tert-butyl hydroperoxide-mediated oxidative coupling of alcohols with
           amines under base free conditions
    • Abstract: Publication date: Available online 12 February 2019Source: Tetrahedron LettersAuthor(s): Ramesh Balaboina, Narasimha Swamy Thirukovela, Ravinder Vadde, Chandra Sekhar Vasam We present a base free method for amide bond construction via oxidative coupling of alcohols with amines catalyzed by Silver(I) N-heterocyclic carbenes (Ag(I)-NHCs) and mediated by tert-butyl hydroperoxide(TBHP) in ethanol. The results of controlled experiments suggest that the oxidative coupling proceeds through the formation of aldehyde, then subsequent attack by amine to give hemiaminal, which can then be oxidized to amide.Graphical abstractGraphical abstract for this article
       
  • Visible-light-mediated Gomberg-Bachmann reaction: an efficient
           photocatalytic approach to 2-aminobiphenyls
    • Abstract: Publication date: Available online 11 February 2019Source: Tetrahedron LettersAuthor(s): Ritu Kapoor, Ruchi Chawla, Lal Dhar S. Yadav An efficient, metal-free and highly selective protocol for the synthesis of 2-aminobiphenyls via visible-light-mediated arylation of anilines using aryl diazonium salts (Gomberg-Bachmann reaction) has been reported. The reaction is an example of photoredox catalysed direct C(sp2)-H arylation of anilines using eosin Y as an organophotoredox catalyst. The presented visible-light-mediated environmentally sustainable approach has the potential to earn a decent position among the classical and contemporary methods for the synthesis of aminobiaryls.Graphical abstractGraphical abstract for this article
       
  • Direct radical sulfonylation at α-C(sp3)-H of THF with sodium sulfinates
           in aqueous medium
    • Abstract: Publication date: Available online 11 February 2019Source: Tetrahedron LettersAuthor(s): Manjula Singh, Lal Dhar S. Yadav, Rana Krishna Pal Singh A direct transition-metal-free, convenient and highly regioselective synthesis of 2-alkyl/aryl sulfonyl tetrahydrofurans (THFs) has been achieved from THF and sodium sulfinates using K2S2O8 as a mild oxidant. This one-pot simple protocol involves an efficient radical cross coupling reaction in aqueous medium utilizing K2S2O8 as an inexpensive and easy to handle radical surrogate at room temperature.Graphical abstractGraphical abstract for this article
       
  • B2pin2-mediated copper-catalyzed oxidation of alkynes into 1,2-diketones
           using molecular oxygen
    • Abstract: Publication date: Available online 11 February 2019Source: Tetrahedron LettersAuthor(s): Yadong Zhai, Zhenni Su, Hao Jiang, Jing Rong, Xianfan Qiu, Chuanzhou Tao An intriguing aerobic oxidation of alkynes through copper catalysis is described, in which bis(pinacolato)diboron (B2pin2) played a dominant intermediary role in the formation 1,2-diketones. This novel protocol, which can be performed at room temperature, is versatile for various substituted alkynes, including diarylalkynes and arylalkylalkynes. The mechanism of this reaction was preliminarily investigated by control experiments.Graphical abstractGraphical abstract for this article
       
  • Cu-catalyzed aerobic oxidative synthesis of sulfonamides from sulfonyl
           hydrazides and amines
    • Abstract: Publication date: Available online 10 February 2019Source: Tetrahedron LettersAuthor(s): Sohyun Chung, Jinho Kim An environmentally friendly route for sulfonamides has been developed. The oxidative coupling of sulfonyl hydrazides and amines was catalyzed by CuBr2 to produce various sulfonamides with the water and nitrogen gas as byproducts. Preliminary experiments revealed that the sulfonyl radical is likely to be involved in the reaction mechanism.Graphical abstractGraphical abstract for this article
       
  • Formal synthesis of (±)-aplykurodinone-1 through an intramolecular
           Michael addition
    • Abstract: Publication date: Available online 10 February 2019Source: Tetrahedron LettersAuthor(s): Ying Peng, Yongli Sun, Bo Wang, Yi Zhou, Shuangping Huang, Xiaoji Wang A concise and straightforward formal synthesis of (±)-aplykurodinone-1, a degraded steroid natural product isolated from sea hare Syphonota geographica is described, based on an intramolecular Michael addition. The route also includes an intermolecular Michael addition, a Riley selenium dioxide oxidation, and a Krapcho dealkoxycarbonylation. The relative stereochemistries of key intermediates have been determined through single-crystal X-ray diffraction analysis.Graphical abstractGraphical abstract for this article
       
  • Erratum to “Preparation of new gem-difluoro heterocyclic-fused
           1,2,3-triazole derivatives” [Tetrahedron Lett. 60 (2019) 292–296]
    • Abstract: Publication date: Available online 10 February 2019Source: Tetrahedron LettersAuthor(s): Layal Hariss, Zeinab Barakat, Farès Farès, Thierry Roisnel, René Grée, Ali Hachem
       
  • Alstobrogaline, an unusual pentacyclic monoterpenoid indole alkaloid with
           aldimine and aldimine-N-oxide moieties from Alstonia scholaris
    • Abstract: Publication date: Available online 10 February 2019Source: Tetrahedron LettersAuthor(s): Premanand Krishnan, Chun-Wai Mai, Kien-Thai Yong, Yun-Yee Low, Kuan-Hon Lim Alstobrogaline (1), an unusual monoterpenoid indole alkaloid incorporating a third N atom and possessing two aldimine functions, with one being in the form of N-oxide, was isolated from the leaves of Alstonia scholaris. Its structure and relative configuration were determined by extensive NMR spectroscopic analysis, while its absolute configuration was established by X-ray diffraction analysis. A possible biogenetic pathway to 1 was proposed. Compound 1 displayed weak cytotoxic effects against MDA-MB-231 and MCF7 breast cancer cells.Graphical abstractGraphical abstract for this article
       
  • Organic base-promoted efficient dehydrogenative/decarboxylative
           aromatization of tetrahydro-β-carbolines into β-carbolines under air
    • Abstract: Publication date: Available online 10 February 2019Source: Tetrahedron LettersAuthor(s): Ziquan Zhao, Yan Sun, Lilin Wang, Xuan Chen, Yanpei Sun, Long Lin, Yulin Tang, Fei Li, Dongyin Chen Organic base DBN has been identified as an efficient reagent for promoting the dehydrogenative/decarboxylative aromatization of tetrahydro-β-carbolines under air atmosphere, to access the corresponding β-carbolines in moderate to good yields. The utility of this protocol for the gram-scale synthesis of β-carboline alkaloids eudistomin U (7) and harmane (10) has also been demonstrated.Graphical abstractGraphical abstract for this article
       
  • Three step, one-pot process to prepare thiophene-2-carbonyl chloride
           
    • Abstract: Publication date: Available online 8 February 2019Source: Tetrahedron LettersAuthor(s): Daniel P. Walker, Charles R. Graham, William H. Miller, Kevin J. Koeller Nematodes are parasitic organisms that cause significant damage to crops. Tioxazafen (Nemastrike®), is a proprietary seed treatment being developed by Bayer AG as a broad-spectrum nematicide. Thiophene-2-carbonyl chloride (TCC) is the key raw material in the manufacture of tioxazafen. Current manufacturing routes to TCC suffer from byproduct formation and significant waste generation, which leads to high manufacturing cost. A potentially more cost-effective process for preparing TCC from commercial thiophene has been developed. The advantages of this new chemical approach are illustrated in the processing details described in this Letter.Graphical abstractGraphical abstract for this article
       
  • Catalytic application of Zinc complex of oxygen depleted
           1,3-Bis(pyrazole)-p-tert-butylcalix[4]arene
    • Abstract: Publication date: Available online 8 February 2019Source: Tetrahedron LettersAuthor(s): Anshu Kumar Sinha, Arkadi Vigalok, Varun Rawat In this paper we have described the synthesis and coordination properties of monometallic Zinc complex of oxygen depleted bis(pyrazole)-p-tert-butylcalix[4]arene ligand. We also present the catalytic activity of the Zinc–bis(pyrazole) complex, in acetylation of alcohols and lactide polymerization.Graphical abstractGraphical abstract for this article
       
  • Enantioselective synthesis of GNE-6688, a potent and selective inhibitor
           of interleukin-2 inducible T-cell kinase (ITK)
    • Abstract: Publication date: Available online 8 February 2019Source: Tetrahedron LettersAuthor(s): Jared Moore, Kevin Lau, Xiaofeng Xu, Yamin Zhang, Jason D. Burch An enantioselective synthesis of the previously-disclosed ITK inhibitor GNE-6688 is described. Synthesis of the nitropyrazole fragment is highlighted by a Ru-catalyzed transfer hydrogenation using the Wills tethered ligand system. Synthesis of the pyrazole carboxylic acid fragment features an allylboration catalyzed by a chiral diol-SnCl4 complex, followed by a highly diastereoselective directed cyclopropanation.Graphical abstractGraphical abstract for this article
       
  • Isothiouronium salts as useful and odorless intermediates for the
           synthesis of thiaalkylimidazolium ionic liquids
    • Abstract: Publication date: Available online 7 February 2019Source: Tetrahedron LettersAuthor(s): Gabriela I. Matiello, Alessandra Pazini, Kácris I.M. da Silva, Rafaela G.M. da Costa, Günter Ebeling, Jairton Dupont, Jones Limberger, Jackson D. Scholten A simple and odorless route for the synthesis of monocationic and dicationic thiaalkylimidazolium ionic liquids (ILs) is reported. Our approach starts with the selective monoalkylation of dihalogenated substrates by methylimidazole derivatives, followed by the synthesis of odorless isothiouronium salts via reaction with thiourea. The target ILs are obtained after sequential hydrolysis-alkylation of the isothiouronium salts followed by anion metathesis in water. After extraction, the novel thiaalkylimidazolium ILs are obtained with high purity, without the requirement of additional purification steps. In order to demonstrate their applicability, two of these task-specific ILs were employed as ligands in Ullmann and Suzuki couplings and also as charged probes to detect copper intermediates via ESI(+)-MS.Graphical abstractGraphical abstract for this article
       
  • Graphical abstract TOC
    • Abstract: Publication date: 21 February 2019Source: Tetrahedron Letters, Volume 60, Issue 8Author(s):
       
  • Graphical abstract TOC
    • Abstract: Publication date: 21 February 2019Source: Tetrahedron Letters, Volume 60, Issue 8Author(s):
       
  • Graphical abstract TOC cont’d
    • Abstract: Publication date: 21 February 2019Source: Tetrahedron Letters, Volume 60, Issue 8Author(s):
       
  • Scalable Synthesis of Cladosporin
    • Abstract: Publication date: Available online 6 February 2019Source: Tetrahedron LettersAuthor(s): Pronay Das, Yash Mankad, D. Srinivasa Reddy Cladosporin, a secondary metabolite isolated from fungal sources like Cladosporium cladosporioides and Aspergillus flavus was found to exhibit selective nano-molar activity against malarial parasite Plasmodium falciparum by inhibiting parasitic protein biosynthesis. In addition, this natural product has a broad range of bioactivities including, antiparasitic, antifungal, antibacterial as well as plant growth inhibition. However, it has limited availability from the natural sources for further development. Herein, we report a modified and improved synthetic route which led us to produce this potent natural product in a gram scale. Conversion of the undesired diastereomer to desired one via Mitsunobu inversion of secondary alcohol and carbon monoxide insertion reaction towards the construction of isocoumarin unit are the key features of the present synthesis.Graphical abstractGraphical abstract for this article
       
  • Zn(OTf)2-catalyzed, microwave-promoted synthesis of 2-substituted
           5-methyloxazoles from propargylic amides
    • Abstract: Publication date: Available online 5 February 2019Source: Tetrahedron LettersAuthor(s): Alexander Safrygin, Dmitry Dar'in, Alexei Lukin, Anna Bakholdina, Alexander Sapegin, Mikhail Krasavin The versatile conversion of propargylic amides to the respective 2-substituted 5-methyloxazoles was efficiently catalyzed by Zn(OTf)2 (5 mol%) under microwave irradiation in toluene. The method was applicable to a wide range of aliphatic, aromatic and heteroaromatic propargylic amides and thus represents a useful method which is complementary to the existing metal-catalyzed protocols, considering the ready availability of Zn(OTf)2.Graphical abstractGraphical abstract for this article
       
  • “Four-Component” Assembly of Polyaromatic 4H-Cyclopenta[b]thiophene
           Structures based on GaCl3-Promoted Reaction of Styrylmalonates with
           5-Phenylthiophene-2-carbaldehyde
    • Abstract: Publication date: Available online 5 February 2019Source: Tetrahedron LettersAuthor(s): Denis D. Borisov, Grigory R. Chermashentsev, Roman A. Novikov, Yury V. Tomilov New “four-component” self-assembly of polyaromatic thiophene structures based on styrylmalonates and 5-phenylthiophene-2-carbaldehyde has been developed. This process is promoted by GaCl3 and involves two [2+3]-annulation steps on the CHO-groups and para-substitution into one Ph-ring. The main feature of discovered process is a high diastereoselectivity with a significant increase in molecular complexity. The resulting polyaromatic structures containing two thiophene moieties in each structure have intense color and strong absorption in a near UV spectral region with absorption maxima in the range of 257–360 nm.Graphical abstractGraphical abstract for this article
       
  • Nukiangendines A and B, two novel 13,14-seco-abietanes from
           Abies nukiangensis
    • Abstract: Publication date: Available online 5 February 2019Source: Tetrahedron LettersAuthor(s): Yong-Li Li, Qiang Zhang, Jian-Jun Wu, Li-Jun Xue, Li-Ming Chen, Jun-Mian Tian, Zhuo-Ni Xu, Ying Chen, Xian-Wen Yang, Xiao-Jiang Hao, Jie Li From Abies nukiangensis, two novel 13,14-seco-abietane diterpenes, nukiangendines A (1) and B (2) were isolated. Their relative structures were determined by extensive NMR and HRMS spectroscopic analysis. The absolute configuration of 1 was established by ECD calculations. Compound 1 showed significant anti-hepatitis C virus (HCV) effects.Graphical abstractGraphical abstract for this article
       
  • Synthesis of novel racemic 3,4-dihydroferroceno[c]pyridines via the Ritter
           reaction
    • Abstract: Publication date: Available online 5 February 2019Source: Tetrahedron LettersAuthor(s): Yuliya S. Rozhkova, Irina V. Plekhanova, Alexey A. Gorbunov, Olga G. Stryapunina, Evgeny N. Chulakov, Victor P. Krasnov, Marina A. Ezhikova, Mikhail I. Kodess, Pavel A. Slepukhin, Yurii V. Shklyaev A new approach for the synthesis of functionalized racemic 3,4-dihydroferroceno[c]pyridines via the Ritter reaction of 2-methyl-1-ferrocenylpropan-1-ol with nitriles in the presence of methansulfonic acid was developed. The scope and limitations of the reaction were evaluated. Selected racemic 3,4-dihydroferroceno[c]pyridines were successfully separated by preparative HPLC on a Chiralcel OD-H column. The absolute configuration of the enantiomers was determined by X-ray crystal structure analysis.Graphical abstractGraphical abstract for this article
       
  • Synthesis and properties of novel extended BODIPYs with rigid skeletons
    • Abstract: Publication date: Available online 5 February 2019Source: Tetrahedron LettersAuthor(s): Yuki Kawamata, Satoshi Ito, Masaru Furuya, Kai Takahashi, Katsuya Namai, Saori Hashimoto, Makoto Roppongi, Toru Oba Novel extended BODIPYs fused with bicyclo rings were synthesized from bicyclopyrroles by combining Knoevenagel condensation, Suzuki coupling, and O-chelation. The absorption maxima of the BODIPYs ranged from the visible to near-infrared region and the compounds showed good solubility in organic solvents. The solubility of the bicycloBODIPY with 2-naphthyl groups at the α-position of the pyrrole units was particularly high. Heating converted distyrylBODIPY with bicyclo[2.2.2]octene to benzoBODIPY with absorption (748.5 nm) and fluorescence (775.0 nm) in the near-infrared region.Graphical abstractGraphical abstract for this article
       
  • Reaction of N-methylazomethine ylide with aroyl azides: synthesis
           of imidazolidin-4-ones
    • Abstract: Publication date: Available online 5 February 2019Source: Tetrahedron LettersAuthor(s): Evgeny M. Buev, Vladimir S. Moshkin, Vyacheslav Y. Sosnovskikh Aryl isocyanates generated in situ from aroyl azides react with N-methylazomethine ylide generated in situ from N-methylspiroanthraceneoxazolidine at 210 °C in a microwave reactor to form 3-arylimidazolidin-4-ones in 30–81% yield.Graphical abstractGraphical abstract for this article
       
  • Total synthesis of natural (−)- and unnatural (+)-Melearoride A
    • Abstract: Publication date: Available online 4 February 2019Source: Tetrahedron LettersAuthor(s): Carson W. Reed, Mark G. Fulton, Kellie D. Nance, Craig W. Lindsley This communication details the first total synthesis of the 13-membered macrolide, (−)-Melearoride A, as well as unnatural (+)-Melearoride A. The synthesis features a concise 13 step synthesis (11 steps longest linear sequence) that offers flexible stereo-control and multiple opportunities for unnatural analog synthesis to delve into antifungal SAR. The route features a cuprate addition, an Evans asymmetric alkylation, and a ring-closing metathesis (RCM) to close the 13-membered macrocyclic core.Graphical abstractGraphical abstract for this article
       
  • Stereoconvergent synthesis of
           N-Boc-(2R,3S)-3-hydroxy-2-phenylpiperidine
    • Abstract: Publication date: Available online 2 February 2019Source: Tetrahedron LettersAuthor(s): Manuel Velasco, Ulises Hernández, Joel L. Terán, Dino Gnecco, María L. Orea, David M. Aparicio, Víctor Gómez-Calvario, Sylvain Bernès, Jorge R. Juárez The stereoconvergent synthesis of N-Boc-(2R,3S)-3-hydroxy-2-phenylpiperidine from (R)-1-(2-((tert-butyldimethylsilyl)oxy)-1-phenylethyl)piperidin-2-one is described. The key steps involved are α-hydroxylation of quiral lactam with O2, stereoconvergent reduction of (R)- or (S)-3-(benzyloxy)-piperidin-2-one with Red-Al® which afforded in both cases the trans-bicyclic oxazolidine in high stereoselectivity after chromatographic purification and a stereospecific Grignard addition to chiral bicyclic oxazolidine.Graphical abstractGraphical abstract for this article
       
  • Macrocyclic bis-urea receptor: synthesis, crystal structure and phosphate
           binding properties
    • Abstract: Publication date: Available online 2 February 2019Source: Tetrahedron LettersAuthor(s): Xi Shu, Ruyu Wang, Yu Fan, Shoujian Li, Chao Huang A macrocyclic bis-urea receptor (L1) and two acyclic bis-urea analogues (L2 and L3) have been synthesized. The crystal structure of L1 was obtained. The experimental results show that the receptor L1 has high selectivity to H2PO4−. Meanwhile, compared with the acyclic receptors L2 and L3, L1 has higher binding ability to H2PO4−. The results of density functional theory (DFT) calculations deepened our understanding on L1 conformations stability and its anion-binding study.Graphical abstractGraphical abstract for this article
       
  • Electrochemical oxidative selenylation of imidazo[1,2–a]pyridines
           with diselenides
    • Abstract: Publication date: Available online 2 February 2019Source: Tetrahedron LettersAuthor(s): Yeon Joo Kim, Dae Young Kim Electrochemical oxidative selenylation of imidazo[1,2–a]pyridines has been developed. The reaction proceeds in an undivided electrochemical cell equipped with glassy carbon electrodes employing LiClO4 as a supporting electrolyte. This approach is environmentally benign by using shelf-stable diselenides as selenium source and electrons as oxidizing reagents. The present protocol offers a facile way to prepare 3-selenylated imidazopyridine derivatives.Graphical abstractGraphical abstract for this article
       
  • Transition-Metal-Free, Visible-Light-Mediated Regioselective C–H
           Trifluoromethylation of Imidazo[1,2-a]pyridines
    • Abstract: Publication date: Available online 2 February 2019Source: Tetrahedron LettersAuthor(s): Qiguang Zhou, Song Xu, Ronghua Zhang A transition-metal-free, visible-light-induced trifluoromethylation of imidazo[1,2-a]pyridines has been developed at mild conditions by employing cheap and commercially available anthraquinone-2-carboxylic acid (AQN-2-CO2H) as the photo-organocatalyst, and Langlois reagent as the trifluoromethylating reagent. A series of 3-(trifluoromethyl)imidazo[1,2-a]pyridine derivatives with broad functionalities could be conveniently and efficiently obtained by direct regioselective functionalization.Graphical abstractGraphical abstract for this article
       
  • Synthesis of Gentianine N-Oxide by Enzymatic Hydrolysis of Swertiamarin in
           the Presence of Hydroxylamine and Reaction Pathway to Gentianine and
           Gentianol
    • Abstract: Publication date: Available online 2 February 2019Source: Tetrahedron LettersAuthor(s): Mikio Fujii, Taiki Kuramochi, Yuhi Nakakuki, Rina Hatazawa, Kiju Konno, Tatsuo Munakata, Yasuaki Hirai Gentianine is a metabolite of gentiopicroside and swertiamarin. Several biological activities have been reported for gentianine, such as antiinflammatory and antidiabetic activity, and hypotensive effect. Gentiopicroside is found in 0.9–9.8% content in Gentian root or Gentian scabra root, and Swertiamarin is contained in Swertia herb in 2–10%. These natural products can be potential starting materials for the synthesis of gentianine. This study describes the β-glucosidase-catalyzed hydrolysis of gentiopicroside and swertiamarin in the presence of hydroxylamine to afford gentianine N-oxide, which can be a synthetic precursor of gentianine derivatives. Enzymatic hydrolysis of swertiamarin selectively afforded gentianine N-oxide in 81% yield, whereas gentiopicroside afforded gentianine N-oxide and gentianol N-oxide. Plausible reaction pathways leading to gentianine, gentianol, and their N-oxides were also investigated.Graphical abstractGraphical abstract for this article
       
  • Synthesis of ethynylpyrene-modified 3-deaza-2'-deoxyguanosines as
           environmentally sensitive fluorescent nucleosides: target DNA-sequence
           detection via changes in the fluorescence wavelength
    • Abstract: Publication date: Available online 2 February 2019Source: Tetrahedron LettersAuthor(s): Takuya Takeda, Masaki Yanagi, Azusa Suzuki, Ryuzi Katoh, Yoshio Saito Novel pyrene-labeled environmentally sensitive fluorescent (ESF) nucleosides [1p3zG (1a) and 2p3zG (1b)] possessing the 3-deazaguanine skeleton were synthesized. Among them, 1p3zG (1a) exhibited longer fluorescence emission wavelengths compared with the previously reported naphthalene-modified ESF nucleoside 3nzG (48-71 nm longer in polar solvents) and showed remarkable solvent-polarity-sensitive fluorescence properties. Oligodeoxynucleotide (ODN) probes containing 1p3zG (1a) clearly discriminated target DNAs by the change in the emission wavelength and intensity through monitoring the microenvironmental change around the DNA minor groove. Thus, these pyrene-labeled ESF nucleosides can be applied in gene detection and molecular diagnostics, as well as in the structural analysis of nucleic acids.Graphical abstractGraphical abstract for this article
       
  • Recent Progress on Catalytic [1,3]-Oxygen Rearrangement Reactions from
           Nitrogen to Carbon Atoms
    • Abstract: Publication date: Available online 1 February 2019Source: Tetrahedron LettersAuthor(s): Itaru Nakamura, Masahiro Terada [1,3]-Rearrangement reactions of an oxygen atom from a nitrogen atom to a carbon atom is an ideal way to synthesize highly elaborate molecules in which nitrogen and oxygen functionalities are vicinally arranged. Recently, it has been disclosed that this intriguing transformation takes place in the presence of Lewis acidic metal catalysts. In this digest, we summarize recent findings on the catalytic [1,3]-oxygen rearrangement reactions, such as direct [1,3]-rearrangement of N-oxygenated enamines and anilines, as well as π-acidic metal-catalyzed cascade reaction involving the [1,3]-rearrangement process.Graphical abstractGraphical abstract for this article
       
  • Palladium-catalyzed intramolecular carbonyl α-arylation for the
           synthesis of 2-tetralones
    • Abstract: Publication date: Available online 1 February 2019Source: Tetrahedron LettersAuthor(s): Lianlian Wang, Kun Zhang, Jie Wu, Chuanjun Song The synthesis of 2-tetralone analogues via the palladium-catalyzed intramolecular α-arylation of 2-(2-bromoaryl)-1,3-dicarbonyl compounds has been described.Graphical abstractGraphical abstract for this article
       
  • Asymmetric synthesis of the cytotoxic lactone (+)-cardiobutanolide and two
           novel analogues
    • Abstract: Publication date: Available online 1 February 2019Source: Tetrahedron LettersAuthor(s): Ivana Kovačević, Mirjana Popsavin, Marko V. Rodić, Vesna Kojić, Velimir Popsavin A new asymmetric synthesis of the naturally occurring styryl lactone cardiobutanolide and two novel analogues have been achieved starting from d-xylose. The key steps of the synthesis included an initial zinc mediated reductive THF-ring opening, stereoselective olefination and Sharpless asymmetric dihydroxylation. It was shown that cardiobutanolide (1) exhibits promising in vitro antitumour properties against certain human neoplastic cell lines. It was more potent than the commercial anticancer agent doxorubicin against three cell lines (K562, HL-60 and Raji).Graphical abstractGraphical abstract for this article
       
  • Room Temperature Pd(0)/Ad3P-Catalyzed Coupling Reactions of Aryl Chlorides
           with Bis(pinacolato)diboron
    • Abstract: Publication date: Available online 31 January 2019Source: Tetrahedron LettersAuthor(s): Jie Dong, Hui Guo, Wei Peng, Qiao-Sheng Hu Room temperature Pd(0)/Ad3P-catalyzed cross-coupling reactions of aryl chlorides with bis(pinacolato)diboron are described. The Pd(0)/Ad3P catalyst, generated from Ad3P-coordinated acetanilide-based palladacycle complex, proved to be an efficient catalyst system for the Miyaura borylation reactions of a variety of aryl chlorides with bis(pinacolato)diboron. The mild reaction condition, the easy availability of the catalyst and good coupling yields make these reactions potentially useful in organic synthesis.Graphical abstractGraphical abstract for this article
       
  • Iron-Catalyzed Aerobic Oxidative Cross-Coupling Amidation of
           N,N-Dimethylanilines
    • Abstract: Publication date: Available online 30 January 2019Source: Tetrahedron LettersAuthor(s): Abudureheman Wusiman, Ruzeahong Hudabaierdi An efficient iron-catalyzed dehydrogenative cross-coupling amidation/imidation reaction between N,N-dimethylanilines and amides/imides is reported. The protocol uses an inexpensive and readily available Fe(NO3)3∙9H2O/O2 catalytic system in the absence of additional ligands at room temperature.Graphical abstractGraphical abstract for this article
       
  • Concise and Stereoselective Synthesis of 2,5- and 2,4-Disubstituted
           Thiazole Amino Acid Subunits for Synthesizing Thiazole-Containing Peptides
           
    • Abstract: Publication date: Available online 30 January 2019Source: Tetrahedron LettersAuthor(s): Takuji Magata, Yoshimi Hirokawa, Yusuke Moriguchi, Ryosuke Yokoi, Shotaro Nojiri, Ryota Miyazaki, Sayuri Akasako, Rina Takahashi, Munetaka Nishida, Junya Hakoda, Ryota Nakayama, Aya Tanaka, Naoyoshi Maezaki A concise, highly stereoselective synthesis of 2,4- and 2,5-disubstituted thiazole amino acids was developed. These are important building blocks for various biologically active thiazole-containing natural peptides and their regioisomeric analogues. The fundamental reactions are diastereoselective addition of (4- or 5-bromothiazol-2-yl)lithium to N-tert-butanesulfinyl imine with subsequent Pd-catalyzed phenoxycarbonylation.Graphical abstractGraphical abstract for this article
       
  • Colorimetric detection of Ni2+ based on an anionic triphenylmethane dye
           and a cationic polyelectrolyte in aqueous solution
    • Abstract: Publication date: Available online 29 January 2019Source: Tetrahedron LettersAuthor(s): Yasumasa Fukushima, Shunichi Aikawa The combination of xylenol orange (XO) and poly(diallyldimethylammonium chloride) (PDADMAC) has been utilized as a colorimetric sensor for selective recognition of Ni2+ in aqueous solution. Upon addition of Ni2+, the chemosensor exhibited the significant color change from red to purple with a bathochromic shift, whereas these change was not induced by other metal ions. XO alone did not recognize Ni2+ colorimetrically, indicating that PDADMAC was required for detecting Ni2+. This study can provide the facile method for the construction of new chemosensors by a simple mixture of an anionic water-soluble dye and cationic polyelectrolyte.Graphical abstractGraphical abstract for this article
       
  • Visible Light Induced Oxidative Hydroxylation of Boronic Acids
    • Abstract: Publication date: Available online 29 January 2019Source: Tetrahedron LettersAuthor(s): Aishun Ding, Yanbin Zhang, Yang Chen, Ramon Rios, Jianhua Hu, Hao Guo We report herein a visible light-induced aerobic oxidative hydroxylation of boronic acids. The reaction employed 7H-benzo[c]thioxanthen-7-one as metal-free catalyst and dimethyl carbonate as green solvent. Scale-up experiment was achieved using 0.1 mol% catalyst in a good yield with column-free purification. This reaction showed great green chemistry features and potential in synthetic applications.Graphical abstractGraphical abstract for this article
       
  • DABCO/AgOAc Cooperatively Catalyzed α-Sulfenylation of Isocyanoacetates
           with N-(Sulfanyl)succinimides
    • Abstract: Publication date: Available online 28 January 2019Source: Tetrahedron LettersAuthor(s): Mei-Xin Zhao, Qiang Liu, Rong-Hui Jiang, Min Shi The first organo/metal cooperatively catalyzed α-sulfenylation of isocyanoactates with N-(sulfanyl)succinimides has been developed. The reaction condition was suitable to α-aryl and alkyl-substituted isocyanoactates as well as N-(arylthio)succinimides, affording the corresponding products with high yields (90-96%). Preliminary asymmetric organocatalysis has also been evaluated.Graphical abstractGraphical abstract for this article
       
  • Regioselective Synthesis of 1,5-Disubstituted 1,2,3-Triazoles by
           1,3-Dipolar Cycloaddition: Role of Er(OTf)3, Ionic Liquid and Water
    • Abstract: Publication date: Available online 28 January 2019Source: Tetrahedron LettersAuthor(s): Loredana Maiuolo, Beatrice Russo, Vincenzo Algieri, Monica Nardi, Maria Luisa Di Gioia, Matteo Antonio Tallarida, Antonio De Nino A simple procedure to obtain 1,5-disubstituted 1,2,3-triazoles, using the Er(OTf)3/[mpy]OTf/H2O catalytic system is described. The reaction proceeds through an eliminative azide–olefin cycloaddition (EAOC) offering a highly regioselective approach and good yields (81–94%). The advantages of this method include simple operations of work-up and the ability of the catalytic system to be re-used five times without an evident loss in yield. The role of IL and water were speculated, invoking also a probable ionic self-assembly (ISA) effect.Graphical abstractGraphical abstract for this article
       
  • Rhodium-Catalyzed C-H Activation/Cyclization of Enaminones with
           Sulfoxonium Ylides toward Polysubstituted Naphthalenes
    • Abstract: Publication date: Available online 28 January 2019Source: Tetrahedron LettersAuthor(s): Zhenlian Wang, Huang Xu A rhodium-catalyzed ortho-C–H functionalization and annulation between enaminones and sulfoxonium ylides was developed, affording a series of multi-substituted naphthalenes in good to moderate yields with excellent functional group compatibility. The procedure featured with enaminone acting as both a directing and cyclization bifunctional group, and the application of sulfoxonium ylide in C–H functionalization.Graphical abstractGraphical abstract for this article
       
  • Simple and Mild Stereoselective O-Glycosidation using 1,2-Anhydrosugars
           Under Neutral Conditions
    • Abstract: Publication date: Available online 26 January 2019Source: Tetrahedron LettersAuthor(s): Devaraj Somasundaram, Kalpattu K. Balasubramanain, Bhagavathy Shanmugasundaram The ring opening of α-d-1,2-anhydrohexapyranoses with phenols proceeded smoothly in ethyl acetate (neutral conditions) in the absence of metal ion catalysts or additives to stereoselectively furnish 1,2-cis-α-aryl glycosides as the major product and 1,2-trans-β-aryl glycosides as the minor product in good yields. Under similar conditions, this ring opening reaction with alcohols afforded exclusively β-alkyl glycosides in excellent yields.Graphical abstractGraphical abstract for this article
       
  • Cascade reaction including a formal [5+2] cycloaddition by use of
           alkyne-Co2(CO)6 complex
    • Abstract: Publication date: Available online 24 January 2019Source: Tetrahedron LettersAuthor(s): Yuki Sakata, Eiko Yasui, Megumi Mizukami, Shinji Nagumo A new cascade reaction including formal [5+2] cycloaddition was developed. Treatment of homocinnamyl alcohol and Co2(CO)6-complexed arylpropynal with BF3·OEt2 resulted in the generation of hydrobenzocycloheptafuran having an alkyne-Co2(CO)6 complex. The reaction consists of 5-membered ring selective Prins cyclization and subsequent Friedel-Crafts cyclization. The cascade reaction was applied to a further multi-step cascade cyclization, which resulted in the formation of more complex polycyclic hydrofurans.Graphical abstractGraphical abstract for this article
       
  • A microwave-assisted approach to N-(2-nitrophenyl)benzenesulfonamides that
           enhanced peroxidase activity in response to excess cadmium
    • Abstract: Publication date: Available online 24 January 2019Source: Tetrahedron LettersAuthor(s): Zhi-You Huang, Min Liu, Yi-Jun Mao, Yu-De Chen, Yan-Ping Wang, Chong Liu A facile and efficient approach to N-(2-nitrophenyl)benzenesulfonamides was developed under microwave irradiation. A series of pyrabactin analogues containing nitrophenyl scaffold was obtained in excellent yields. In addition, the method was pretty suitable to prepare flusulfamide. Significantly, the 3ae could enhance POD activity in response to heavy metal stress.Graphical abstractGraphical abstract for this article
       
  • Nonstabilized azomethine ylides in the synthesis of aryl cucurbitine
           derivatives
    • Abstract: Publication date: Available online 24 January 2019Source: Tetrahedron LettersAuthor(s): Evgeny M. Buev, Anastasia A. Smorodina, Vladimir S. Moshkin, Vyacheslav Y. Sosnovskikh Nonstabilized azomethine ylides react with 4-arylidene-2-phenyloxazol-5(4H)-ones to form diazaspiro[4.4]nonenes, which were hydrolyzed to aryl cucurbitine derivatives in 35–67% overall yield.Graphical abstractGraphical abstract for this article
       
  • Synthesis of Alkyl Dithiocarbamates by Using Thiuram Disulfide Reagents: a
           Metal-free C(sp3)-S Bond Formation
    • Abstract: Publication date: Available online 24 January 2019Source: Tetrahedron LettersAuthor(s): Yu Cheng, Han-Ying Peng, Zhi-Bing Dong An efficient and environmentally benign protocol for the synthesis of S-alkyl dithiocarbamates has been achieved. By reacting tetraalkylthiuram disulfides with alkyl halides, the desired products could be obtained in good to excellent yields. The methodology features efficiency, transition-metal-free, nice yields and easy performance, illustrating it practical synthetic value for the convenient preparation of some potential biologically active molecules.Graphical abstractGraphical abstract for this article
       
  • Synthetic studies toward swinhoeisterol A, a novel steroid with an unusual
           carbon skeleton
    • Abstract: Publication date: Available online 24 January 2019Source: Tetrahedron LettersAuthor(s): Atsuhiro Takano, Yiwen Zhao, Takayuki Ohyoshi, Hideo Kigoshi Swinhoeisterol A is a novel steroid with unusual 6/6/5/7 tetracyclic skeleton. The model compound with BCD rings is constructed by Friedel–Crafts acylation and an oxidative dearomatization as key steps.Graphical abstractGraphical abstract for this article
       
  • New Chiral Morpholine-Pyrrolidine Ligands Affecting Asymmetric Selectivity
           in Copper Catalyzed Henry Reaction
    • Abstract: Publication date: Available online 24 January 2019Source: Tetrahedron LettersAuthor(s): Venkatachalam Angamuthu, Dar-Fu Tai In this study, several chiral diamine (35, 36, 37 and 39), triamine (24 and 25), diaminol (38, 42 and 43) and triaminol ligands (29 and 30) having chiral morpholine and pyrrolidine moieties conjugated constitutes, were prepared from commercially available (S)-2-amino-2-phenylacetic acid and (S)-proline. These ligands were complexed with copper (Ⅱ) salt in situ and applied to asymmetric Henry reaction. Asymmetric addition of various structurally divergent aldehydes and nitromethane in the presence of 5 mol% of chiral ligand with CuCl2 furnished corresponding β-nitro alcohol in good yields (up to 55-79 %) with good enantioselectivity (up to 89 %).Graphical abstractGraphical abstract for this article
       
  • 44-Methylgambierone, a new gambierone analogue isolated from
           Gambierdiscus australes
    • Abstract: Publication date: Available online 23 January 2019Source: Tetrahedron LettersAuthor(s): J. Sam Murray, Andrew I. Selwood, D. Tim Harwood, Roel van Ginkel, Jonathan Puddick, Lesley L. Rhodes, Frode Rise, Alistair L. Wilkins A new analogue of gambierone, 44-methylgambierone, was isolated from the benthic dinoflagellate Gambierdiscus australes collected from Raoul Island (Rangitahua/Kermadec Islands). This molecule has been previously reported as maitotoxin-3. The structure of 44-methylgambierone was elucidated using 1D- and 2D-nuclear magnetic resonance spectroscopy and mass spectrometry techniques. The nine-ring polyether backbone (A–I) and functional groups (carbonyl, terminal diol, 1,3-diene and monosulphate) are the same for both compounds with the addition of an olefinic methyl group being the only modification in 44-methylgambierone.Graphical abstractGraphical abstract for this article
       
  • NiCl2-Catalyzed Radical Cross Decarboxylative Coupling between
           Arylpropiolic Acids and Cyclic Ethers
    • Abstract: Publication date: Available online 22 January 2019Source: Tetrahedron LettersAuthor(s): Zi-juan Wan, Jin-yuan Wang, Jun Luo A direct alkenylation of cyclic ethers via radical cross decarboxylative coupling process catalyzed by NiCl2 and using DTBP as radical initiator and oxidant was developed. A variety of arylpropiolic acids and cyclic ethers were transformed into the corresponding 2-arylvinyl cyclic ethers in moderate to excellent yields. Mechanistic experiments were conducted to determine the nature of the reaction intermediates, and a plausible reaction mechanism involving NiCl2-promoted radical process was proposedGraphical abstractGraphical abstract for this article
       
  • Japonicones A-C: three lindenane sesquiterpenoid dimers with a 12-membered
           ring core from Chloranthus japonicus
    • Abstract: Publication date: Available online 22 January 2019Source: Tetrahedron LettersAuthor(s): Huan Yan, Xu-Jie Qin, Xu-Hong Li, Qian Yu, Wei Ni, Li He, Hai-Yang Liu Japonicones A-C (1-3), three new dimeric lindenane-type sesquiterpenoids featuring a rare 12-membered ring framework, were isolated from the whole plants of Chloranthus japonicus Sieb. Their structures and absolute configurations were unequivocally established by a combination of spectroscopic data, ECD calculation, and X-ray crystallography. Compounds 1-3 were evaluated for their DNA Topoisomerase Ⅰ (Top1) inhibitory, cytotoxic, and antibacterial activities.Graphical abstractGraphical abstract for this article
       
  • Total synthesis of anithiactins A-C and thiasporine A
    • Abstract: Publication date: Available online 21 January 2019Source: Tetrahedron LettersAuthor(s): I. Caroline Vaaland, Emil Lindbäck, Magne O. Sydnes The total syntheses of anithiactins A-C (1-3) and thiasporine A (4) have been achieved in good overall yields. The key reaction in the synthetic sequence was the Suzuki-Miyaura cross-coupling between 2-aminophenylboronic acid hydrochloride and methyl 2-bromothiazole-4-carboxylate forming the common intermediate methyl 2-(2-aminophenyl)thiazole-4-carboxylate (8), which could be further transformed by hydrolysis, alkylation, and aminolysis to give the four title natural products. This work represents the first total synthesis of anithiactin B (2) and C (3).Graphical abstractGraphical abstract for this article
       
  • An alternative synthesis of the lipophilic tail portion of abediterol
           using linear-selective hydroformylation
    • Abstract: Publication date: Available online 21 January 2019Source: Tetrahedron LettersAuthor(s): Rachel H. Munday, Louis Goodman, Gary M. Noonan Abediterol is a compound currently in development for the treatment of respiratory disease at AstraZeneca. In this work we employ hydroformylation, an under-utilised reaction in the synthesis of pharmaceutical intermediates, as a key step to access the lipophilic amine portion of this molecule. The route described herein addresses some of the issues identified in the original route. Namely, hazardous materials are avoided and increased levels of control - from a process chemistry point of view - are demonstrated, with isolation of intermediates possible at multiple points in the synthesis. This work provides ‘proof-of-concept’ for an alternative synthetic route and provides high-quality material using a series of robust transformations.Graphical abstractGraphical abstract for this article
       
  • Synthetic applications of rongalite: A green tool in the service of
           Diels-Alder chemistry and beyond
    • Abstract: Publication date: Available online 19 January 2019Source: Tetrahedron LettersAuthor(s): Sambasivarao Kotha, Priti Khedkar, Yuvaraj Dommaraju Rongalite or sodium hydroxymethanesulfinate dihydrate acts as a bleaching agent and it is used in printing and dying industry. Due to its ability to deliver SO2 dianion, rongalite is useful to prepare sultines and sulfones. We have been exploiting its potential towards the construction of diverse polycylic frameworks. This account describes the utility of rongalite to expand the Diels–Alder chemistry via sultine or sulfone derivatives. In this context, rongalite played a critical role to increase the chemical space of unnatural amino acids, spirocycles, polycycles, sulfones and crown ethers.Graphical abstractGraphical abstract for this article
       
  • Rh-catalyzed Intramolecular Cyclization of 1-Sulfonyl-1,2,3-triazole and
           Sulfinate. Concise Preparation of Sulfonylated Unsaturated Piperidines
    • Abstract: Publication date: Available online 19 January 2019Source: Tetrahedron LettersAuthor(s): Ayana Furukawa, Takeshi Hata, Masayuki Shigeta, Hirokazu Urabe When 4-[3-(methanesulfinyloxy)propyl]-1-(arenesulfonyl)-1,2,3-triazoles were treated with rhodium catalysts of the type Rh2(RCO2)4, a new intramolecular cyclization took place to afford 2,3-didehydro-1-(arenesulfonyl)-3-(methanesulfonyl)piperidines in good yields. This reaction most likely proceeds via a new reorganization of bonds in the same molecule, consisting of the addition of the sulfur atom of sulfinate ester to the α-(sulfonylimino)carbene moiety generated from the sulfonyltriazole, followed by the counter attack of the sulfonylimino nitrogen to the carbon bearing the oxygen terminus of sulfinate ester.Graphical abstractGraphical abstract for this article
       
  • Multicomponent domino protocol for the stereoselective synthesis of novel
           pyrrolo[3,2–c]quinolinone hybrid heterocycles
    • Abstract: Publication date: Available online 18 January 2019Source: Tetrahedron LettersAuthor(s): Natarajan Arumugam, Abdulrahman I. Almansour, Raju Suresh Kumar, Mohammad Altaf, S.M. Mahalingam, Govindasami Periyasami, J. Carlos Menéndez, Abdul Jaleel Mohammad Ali Al-Aizari A series of structurally intriguing novel pyrrolo[3,2–c]quinolinone heterocyclic hybrids have been synthesized for the first time via a one-pot multicomponent domino reaction sequence that involves a 1,3-dipolar cycloaddition and two subsequent annulation steps. Baylis-Hillman adducts derived from various substituted benzaldehyde and methyl acrylate in presence of DABCO were used as a dipolarophiles, while the 1,3-dipole components were azomethine ylides, formed in situ from isatin derivatives and L-phenylalanine. The reaction generated five new bonds, three new rings and four contiguous stereocenters, which were created with full diastereomeric control.Graphical abstractGraphical abstract for this article
       
  • Synthesis of trifluoromethyl-group-containing cyclopentadienones by the
           palladium-catalyzed [2+2+1] cycloaddition of aryl- and
           trifluoromethyl-group substituted internal alkynes and carbon monoxide
    • Abstract: Publication date: Available online 18 January 2019Source: Tetrahedron LettersAuthor(s): Shogo Murakami, Taro Sonehara, Kousuke Iwakami, Hiroaki Tsuji, Motoi Kawatsura We investigated the palladium-catalyzed [2+2+1] cycloaddition of aryl- and trifluoromethyl-group-substituted internal alkynes and carbon monoxide, and revealed that the PdBr2 effectively catalyzed the intended reaction. The PdBr2-catalyzed reaction smoothly proceeded and provided aryl- and trifluoromethyl-group-containing cyclopentadienone derivatives in up to 92% yield.Graphical abstractGraphical abstract for this article
       
  • Mycopyranone: a 8,8ˈ-binaphthopyranone with potent anti-MRSA activity
           from the fungus Phialemoniopsis sp
    • Abstract: Publication date: Available online 17 January 2019Source: Tetrahedron LettersAuthor(s): José Rivera-Chávez, Lindsay Caesar, Juan J. Garcia-Salazar, Huzefa A. Raja, Nadja B. Cech, Cedric J. Pearce, Nicholas H. Oberlies A new 8,8ˈ-binaphthopyranone (mycopyranone, 1) was isolated from a solid fermentation of Phialemoniopsis sp. (fungal strain MSX61662), and the structure was elucidated via analysis of the NMR and HRESIMS data. The axial chirality of 1 was determined to be M by ECD. The central chirality at C-4/C-4ˈ was assigned through a modified Mosher’s method, while the absolute configuration at C-3/C-3ˈ was deduced based on analysis of the 3JH-3-H-4 values and NOESY correlations. Compound 1 was evaluated for its antimicrobial properties against Staphylococcus aureus SA1199 and a clinically relevant methicillin-resistant S. aureus strain (MRSA USA300 LAC strain AH1263). Compound 1 inhibited the growth of both strains in a concentration dependent manner with IC50 values in the low μM range. Molecular docking indicated that compound 1 binds to the FtsZ (tubulin-like) protein in the same pocket as viriditoxin (2), suggesting that 1 targets bacterial cell division.Graphical abstractGraphical abstract for this article
       
  • Copper(I)-Catalyzed Direct C-H Trifluoromethylation of Imidazoheterocycles
           with Togni’s Reagent
    • Abstract: Publication date: Available online 17 January 2019Source: Tetrahedron LettersAuthor(s): Ruonan Wang, Jingcai Wang, Qingxuan Tang, Xin Zhao, Junfeng Wang, Yuting Leng, Yangjie Wu, Junbiao Chang, Yusheng Wu, Zhaoda Zhang, Shiwei Wang A mild and efficient trifluoromethylation of imidazopyridines with Togni’s reagent in the presence of inexpensive base has been realized at room temperature. This methodology has several advantages: (1) using efficient copper(I) as catalyst and inexpensive K3PO4 as base, (2) no additional oxidants required for this reaction. (3) good functional group tolerance. An array of trifluoromethylated imidazopyridines with broad functionalities were obtained in acceptable yields.Graphical abstractGraphical abstract for this article
       
  • Novel and efficient synthesis of triazolobenzodiazepine analogues through
           the sequential Ugi 4CR-click-N-arylation reactions
    • Abstract: Publication date: Available online 7 January 2019Source: Tetrahedron LettersAuthor(s): Mohammad Sadegh Asgari, Mehdi Soheilizad, Parviz Rashidi Ranjbar, Bagher Larijani, Rahmatollah Rahimi, Mohammad Mahdavi An efficient approach for the synthesis of N-alkyl-2-aryl-2-(6-oxo-4H-benzo[f][1], [2], [3]triazolo[1,5-a][1], [4]diazepin-5(6H)-yl)acetamides is described. The protocol involves Ugi four-component reaction of 2-bromobenzoic acid, propargylamine, aldehydes and isocyanides followed by in situ sequential click reaction of azide ion with triple bond and N-arylation reaction to afford desired products in good to excellent yields.Graphical abstractGraphical abstract for this article
       
  • Direct catalytic asymmetric method for the synthesis of
           tetrahydropyranopyrazoles through allene zwitterion chemistry
    • Abstract: Publication date: Available online 6 January 2019Source: Tetrahedron LettersAuthor(s): Raghupathi Mutyala, R. Venkatram Reddy, Ravikiran Donthi, V.S. Ramakrishna Kallaganti, Rajesh Chandra The enantioselective synthesis of the tetrahydropyranopyrazole scaffold has been achieved. The quinidine catalyzed reaction of allenoates with arylidenepyrazolones proceeded with high enantio- and diastereoselectivity while the reactions of alkylidenepyrazolones were less efficient. Allene ketones also afforded tetrahydropyranopyrazole derivatives in high yields, however, with only moderate enantioselectivity. The primary adduct undergoes further functional group transformations without effecting the initially formed chiral centre.Graphical abstractGraphical abstract for this article
       
  • Reduction of phosphine oxides to phosphines
    • Abstract: Publication date: Available online 30 December 2018Source: Tetrahedron LettersAuthor(s): Evgeniya Podyacheva, Ekaterina Kuchuk, Denis Chusov The digest is devoted to the most widespread reducing agents which are used for the reduction of tertiary and secondary phosphine oxides, phospholene oxides, phospholane oxides, phosphonates, phosphinates, α- and β-hydroxy and thiomethyl phosphine oxides, α-aminophosphonates α-aminophosphine oxides. Stereoselectivity of reactions is described. Methods of stabilization of phosphines which are prone to re-oxidation by the formation of borane-adduct or metal complexes are considered.Graphical abstractGraphical abstract for this article
       
  • Ru-catalyzed synthesis of substituted phthalides through C–H bond
           activation and functionalization
    • Abstract: Publication date: Available online 3 December 2018Source: Tetrahedron LettersAuthor(s): Maryam Fardpour, Ali Darvish, Ebrahim Kianmehr, Ali Nemati Kharat Synthesis of substituted phthalides through a ruthenium-catalyzed reaction of phthalic anhydrides with acrylates is described. The reaction proceeds via CH bond activation and leads to the formation of vinylated phthalides through a successive double vinylation accompanied by decarboxylation and annulation reactions.Graphical abstractGraphical abstract for this article
       
 
 
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