ALBERT

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 33〈/p〉 〈p〉Author(s): Mitali Mishra, Seetaram Mohapatra, Nilima Priyadarsini Mishra, Bighnanshu K. Jena, Pravati Panda, Sabita Nayak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heterocyclic compounds particularly five, six and seven membered ring containing heterocycles are the most abundant which constitute a staggeringly diverse and important class of molecules that occur ubiquitously in a variety of synthetic drugs, bioactive natural products, pharmaceuticals and agrochemicals. Owing to the glorious past and impressive present of the biologically active heterocyclic scaffolds, these skeletons have long been a subject of immense interest. Hence, substantial efforts have been made to the development of new and innovative synthetic strategies for the synthesis of these heterocycles involving use of different metal catalysts, organic and inorganic reagents etc. Among the different types of metal catalysts used, iron catalysts are one of the cheap and easily available. In recent time, several new and innovative iron(III) chloride catalyzed synthesis of heterocycles with structural diversity are coming in the forefront of the literature by the scientific community. This review highlights the advancements made so far by iron(III) chloride for the synthesis of different assemblies of small heterocycles covering the year 2014–2018.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306628-ga1.jpg" width="261" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 31〈/p〉 〈p〉Author(s): Tao-Shan Jiang, Yuhui Zhou, Long Dai, Xiaojun Liu, Xiuli Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A metal-free 〈em〉p〈/em〉-toluenesulfonic acid (TsOH·H〈sub〉2〈/sub〉O) mediated synthesis of 3-ketoquinolines from anilines, enaminones and DMSO has been developed. In this transformation, DMSO was activated by TsOH·H〈sub〉2〈/sub〉O and provided the one-carbon unit of the 3-ketoquinolines. A plausible mechanism involving an electrophilic sulfenium ion intermediate was proposed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306562-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 31〈/p〉 〈p〉Author(s): Lifeng Wang, Qingshan Tian, Chen Bin, Guozhu Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel copper-catalyzed amination of ethers using isocyanates and DTBP is developed. The reaction provides a unique approach to the synthesis of Boc-protected α-aminals through three-component radical cascade reactions. It provides an alternative method for the construction of this type of valuable motifs in high yield. Meanwhile, the method exhibits high tolerance of various functional groups, such as ether, halide, ester and acyl functionalities.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306598-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Hironori Okamura, Takanobu Fujioka, Naoki Mori, Tohru Taniguchi, Kenji Monde, Hidenori Watanabe, Hirosato Takikawa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Salinipostins are cyclic enol-phosphotriesters isolated from a marine-derived 〈em〉Salinispora〈/em〉 sp. as antimalarial compounds. Herein, the first enantioselective synthesis of salinipostin A was achieved. Organocatalyst-mediated asymmetric cyclopropanation and regioselective cyclopropane ring opening were the key steps.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306549-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Soumen Biswas, Anubha Yadav, Debashis Majee, Shaikh M. Mobin, Sampak Samanta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple, efficient, one-pot sequential process for the preparation of a family of 8,9-dihydropyrido[1,2–〈em〉a〈/em〉]indol-6(7H)-one scaffolds in acceptable yields has been established under mild conditions. The Michael-hemiaminalization-oxidation reaction proceeds between methyl 2-(3-formyl-1〈em〉H〈/em〉-indol-2-yl) acetate and 〈em〉trans〈/em〉-β-aryl/alkyl-substituted acroleins using pyrrolidine-BzOH as an efficient organocatalyst, followed by oxidation of in situ generated of C,〈em〉N〈/em〉-fused hemiaminal adducts in the presence of PDC at room temperature. Excitingly, organobase-catalyzed highly diastereoselective (up to ≤9:1 dr) construction of a series of pharmacologically attractive 1,2,3-fused tetracyclic indole scaffolds with five contiguous chiral centers including an all-carbon stereogenic center has been realized through our developed method. Moreover, pyrrolidine-BzOH and PTSA as combined catalytic systems promote the uninterrupted sequential Michael-cyclization reaction, followed by 〈em〉N〈/em〉-alkylation reaction with carbazole to produce interesting class of 6-(9〈em〉H〈/em〉-carbazol-9-yl)-6,7,8,9-tetrahydropyrido[1,2–〈em〉a〈/em〉]indole derivatives in a diastereoselective manner.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306574-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Mahender Khatravath, Naveen Kumar Mallurwar, Saidulu Konda, Jagan Gaddam, Pallavi Rao, Javed Iqbal, Prabhat Arya〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A practical stereoselective synthesis of the central C1–C10 fragment of eribulin and its two diastereomeric analogues is developed. Our approach relied on the use of 〈span〉l〈/span〉-ascorbic acid as the starting material which allowed accessing a key intermediate with a syn diol moiety (C9 and C10 of eribulin) and a carboxylic ester group. A functionalized six membered lactone having several required hydroxyl groups was then obtained. In a number of steps, the lactone was converted to an intermediate for our key 〈em〉oxa〈/em〉-Michael reaction. A regio- and stereocontrolled intramolecular oxa〈em〉-〈/em〉Michael reaction completed the synthesis of the C1–11 fragment having a trans-fused tetrahydropyrans with the exact stereochemistry of various hydroxyl groups, as in eribulin.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306525-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 30〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 25 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 30〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 5 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Vladislav Y. Korotaev, Igor B. Kutyashev, Alexey Y. Barkov, Yuliya S. Rozhkova, Irina V. Plekhanova, Yurii V. Shklyaev, Vyacheslav Y. Sosnovskikh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ferrocene analogues of pyrrolo[2,1-〈em〉a〈/em〉]isoquinoline alkaloids, 2-(trifluoromethyl)-5,6-dihydroferroceno[〈em〉g〈/em〉]indolizine and 6-(trifluoromethyl)-8,9-dihydro-6〈em〉H〈/em〉-chromeno[4,3-〈em〉b〈/em〉]ferroceno[〈em〉g〈/em〉]indolizines, were obtained in 44–65% yield 〈em〉via〈/em〉 the Grob reaction between 1-nitro-1-(2,2,2-trifluoroethylidene)alkanes or 3-nitro-2-(trifluoromethyl)-2〈em〉H〈/em〉-chromenes and 1-alkyl-3,4-dihydroferroceno[〈em〉c〈/em〉]pyridines in 2-propanol at reflux.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306537-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 30〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 1 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 31〈/p〉 〈p〉Author(s): Hemi Borgohain, Sajal Kumar Das〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of 11-aryl-11〈em〉H〈/em〉-indeno[1′,2′:4,5]imidazo[1,2-〈em〉a〈/em〉]pyridines was obtained via AlCl〈sub〉3〈/sub〉-promoted, dehydrative cyclization of the corresponding aryl(2-arylimidazo[1,2-〈em〉a〈/em〉]pyridin-3-yl)methanols in moderate to good yields. The synthesized compounds can be considered as conformationally restricted, privileged aza-heterocyclic scaffold bearing triarylmethane analogs.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306392-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 2 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Thomas P. Nicholls, Alex C. Bissember〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The scope, applications, and understanding of photoinduced, copper-catalysis have advanced considerably in recent times. Many of these transformations exploit the distinctive properties of photoactive copper species to establish original synthetic methodology and reveal novel reactivity. In this regard, the bifunctionality of copper photocatalysts has often allowed these species to direct and influence synthetic processes in new, interesting, and exciting ways. This article summarizes recent advances in the development of copper photoredox catalysts and provides an overview of the emerging applications of these, and related systems, in organic synthesis.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306033-ga1.jpg" width="497" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Toru Amaya, Yuqing Jin, Mamoru Tobisu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Gomberg-Bachmann reaction is an intermolecular aryl-aryl cross-coupling reaction using an arenediazonium salt and an arene. This digest review surveys recent advances in the Gomberg-Bachmann reaction. More specifically, it focuses on reaction systems that include 1) transition-metal-induced systems, 2) organic promoter-induced systems, 3) electrolytic systems, 4) photoredox systems, and 5) hybrid systems that involve photoredox and transition-metal catalysts.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308226-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Yosuke Taniguchi, Xiuming Cao, Shigeki Sasaki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The efficient synthesis of the highly-deuterated thymidine-〈em〉d〈sub〉9〈/sub〉〈/em〉 by the glycosylation reaction between a deuterated nucleobase and deuterated sugar is described. It is also incorporated into the oligonucleotides using a DNA synthesizer. Using this approach, it is possible to make highly-deuterated oligonucleotides for biological studies and structural analyses.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307944-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 9 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Tong-Lin Wang, Hai-Tang Qi, Xi-Cun Wang, Zheng-Jun Quan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An iodine-catalyzed direct allylation of chiral oxazolidinones with aldehydes and alkenes has been developed. The reaction proceeds, without use of any bases or metals, directly converted the 3-chiral oxazolidinones into 〈em〉N〈/em〉-allylated oxazolidinones. Additionally, the 3-chiral allylamine skeleton was constructed and the diastereomers were isolated by simple column chromatography.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306641-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 10 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Masafumi Hirano, Nobuyuki Komine, Eri Arata, Tatiana Gridneva, Atsuya Hatori, Naoki Kaizawa, Kohei Kamakura, Ayumi Kuramochi, Shinnosuke Kurita, Shuhei Machida, Harumi Okada, Asami Sawasaki, Takumi Uchino〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of achiral and chiral diene and the related ligands in transition-metal complexes is evaluated by percent buried volume (%〈em〉V〈/em〉〈sub〉bur〈/sub〉) based on their molecular structures by X-ray analysis. Steric bulk of cyclic diene ligands in [Ru(acac)〈sub〉2〈/sub〉L] and [RhClL]〈sub〉2〈/sub〉 are sorted in the order of %〈em〉V〈/em〉〈sub〉bur〈/sub〉. Recent developments on transition-metal catalyses using these ligands such as (〈em〉i〈/em〉) conjugate arylations, alkenylation, and alkynylation, (〈em〉ii〈/em〉) imine-arylations and alkenylations, (〈em〉iii〈/em〉) kinetic resolutions, (〈em〉iv〈/em〉) allylation, (〈em〉v〈/em〉) cyclizations, (〈em〉vi〈/em〉) defluorinations, (〈em〉vii〈/em〉) C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H bond activations, and (〈em〉viii〈/em〉) cross-dimerizations are reviewed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306616-ga1.jpg" width="403" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Sampa Gupta, Alisha Ansari, Koneni V. Sashidhara〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A useful and efficient approach for the synthesis of nitroarenes from several aromatic amines (including heterocycles) using peroxide and base has been developed. This oxidative reaction is very easy to handle and afforded the products in good yields. Formation of benzamides from benzylamine was also successfully carried out with this metal-free catalytic system in good to excellent yields.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308391-ga1.jpg" width="498" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Polina S. Teterina, Mariia M. Efremova, Ekaterina V. Sirotkina, Alexander S. Novikov, Olesya V. Khoroshilova, Alexander P. Molchanov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 1,3-dipolar cycloaddition of keto- and aldonitrones with 〈em〉N〈/em〉-arylitaconimides proceeds regioselectively giving only 5-spiroisoxazolidines. In the case of aldonitrones the reaction proceeds with high diastereoselectivity. A range of the obtained adducts were subjected to reductive cleavage of the N〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O bond using zinc powder in acetic acid to give the corresponding spirolactones and 1,3-amino alcohols.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308238-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 9 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Richard Le Sueur, Matt Guest, Lee Belding, Melanie Pilkington, Travis Dudding〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work demonstrates how modulating hydrogen bonding between intermolecular, bifurcated, and intramolecular interactions can be used to tune the structural, electronic, and photophysical properties of cyclopropenium ions and their respective fluorophores. The basis of this switchability was examined using X-ray diffraction analysis, 〈sup〉1〈/sup〉H NMR spectroscopy, DFT calculations, and fluorescence spectroscopy.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306653-ga1.jpg" width="404" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Matic Proj, Izidor Sosič, Stanislav Gobec〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The benzimidazole-2-thione scaffold is present in many drugs encompassing various therapeutic areas. Due to the broad spectrum of bioactivities it also represents an important starting point in drug discovery campaigns, especially those based on fragment-based design. Despite simple structures the tautomerism and regioisomerism of substituted benzimidazole-2-thiones makes unambiguous structural analysis difficult. Tautomeric duplicates are present in commercial libraries resulting in two tautomers being sold as different products. To showcase an example of appropriate structural determination, we synthesized and characterized a set of benzimidazole-2-thiones with different positions of a chlorine atom on the ring. Using NOESY and 〈sup〉13〈/sup〉C NMR spectroscopy, we determined that the thione tautomer predominates in the thione-thiol equilibrium. Furthermore, NOESY and HMBC experiments confirmed the position of the substituents on the benzimidazole-2-thione ring.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040391930841X-ga1.jpg" width="479" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Min Liu, Yu-Wen Liu, Hui Xu, Hui-Xiong Dai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A palladium-catalyzed intramolecular C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H acylation of indole with thioester is described, providing a direct and effective approach for the synthesis of the biologically active indole-indolone scaffolds. The method obviates the need for the prefunctionalized starting materials including organometallic reagents, alkyl halides, and NHP esters in previous metal-catalyzed cross-coupling reaction with thioester. Substrates bearing sensitive halo groups are compatible in the reaction, leaving a functional handle for further structural elaborations.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308214-ga1.jpg" width="492" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Shuaijun Han, Qingsong Wu, Lucas Mele, Licheng Ding, Jingya Li, Dapeng Zou, Yusheng Wu, Yangjie Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple and efficient copper-catalyzed monofluoromethylation of 8-aminoquinolines with 2-bromo-2-fluoroacetate has been described with HPO(OMe)〈sub〉2〈/sub〉 (dimethyl phosphonate) as reductant. The reaction tolerates a variety of quinoline amides and monofluoroalkyl bromides. Significant advantages of this protocol include synthetic convenience and high reaction efficiency.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308408-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Won Sik Na, Pushap Raj, Narinder Singh, Doo Ok Jang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple and selective chemosensor, 〈strong〉A〈/strong〉, was developed for recognizing Cu〈sup〉2+〈/sup〉. The emission spectra of receptor 〈strong〉A〈/strong〉 showed a fluorescence quenching response upon addition of Cu〈sup〉2+〈/sup〉 with a low detection limit of 4.51 nM, significantly less than the WHO recommended guideline for drinking water. In addition, the formed 〈strong〉A∙〈/strong〉Cu〈sup〉2+〈/sup〉 complex was examined for secondary sensing of anions. The 〈strong〉A∙〈/strong〉Cu〈sup〉2+〈/sup〉 complex showed selectivity for CN〈sup〉-〈/sup〉 via a recovering emission profile of 〈strong〉A〈/strong〉.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040391930838X-ga1.jpg" width="323" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): Ziba Rafiee Samani, Abdolmohammad Mehranpour〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel 5-substituted isophthalates were synthesized from the reaction of 2-substituted 1,3-bis(dimethylamino)-trimethinium salts with 1,3-bis(alkoxycarbonyl)acetone derivatives in the presence of sodium methoxide in ethanol at reflux.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307592-ga1.jpg" width="330" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): Hongbo Wei, Hongli Zhang, Shoule Han, Shan Mu, Ke Huang, Guzhou Chen, Weiqing Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Asymmetric synthesis of the marine nor-sesquiterpenoid (+)-austrodoric acid and (+)-austrodoral in seven and nine steps respectively from Wieland-Miescher ketone was described herein. The synthesis featured an oxidative ring contraction of α-formyl cyclic ketone mediated by H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 to forge the hydrindane scaffold together with the contiguous quaternary carbon centers simultaneously.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307245-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): Liliia Usmanova, Dmitry Dar'in, Mikhail Krasavin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Downstream modification of piperazin-2-ones obtained by the Castagnoli-Cushman reaction leads to a novel version of the medicinally relevant 1,2,5-benzothiadiazepin-4-one-1,1-dioxide scaffold. The relative stereochemistry remained 〈em〉trans〈/em〉 as evidenced by the spectroscopic data and the single-crystal X-ray analysis.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307609-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): Sergey Miltsov, Mikhail Goikhman, Alexander Yakimansky, Alexander Misharev, Mar Puyol, Julian Alonso〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The bromination of unsymmetrical indodicarbocyanine dyes bearing electron-donating groups (–NHCOCH〈sub〉3〈/sub〉, –OH) on the aryl rings using 〈em〉N〈/em〉-bromosuccinimide produces dimeric molecules together with the corresponding 〈em〉meso〈/em〉-brominated dyes. The direction of the process depends on the reaction conditions. A possible reaction mechanism is also discussed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307622-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 19 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Jinyu Sun, Jesse Vanloon, Hongbin Yan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report herein that exposure of DNA to microwave irradiation at constant temperature leads to faster strand exchange, as compared with same experiments carried out in a water bath at the same temperature. Furthermore, polymerase chain reactions carried out under microwave irradiation were faster than those in a water bath at the same temperature as well. While the causes of these differences are unclear at this time, this research suggests that microwave irradiation can lead to subtle changes in DNA structural dynamics and functions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308202-ga1.jpg" width="357" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 17 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Tian-Ze Li, Chang-An Geng, Ji-Jun Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The first total synthesis of rhuscholide A, a benzofuran lactone possessing anti-HIV-1 activity, had been accomplished in 14 linear steps with 10.6% overall yield. In this synthesis, base-mediated phenol 〈em〉ortho〈/em〉-alkylation and piperidine promoted aldol condensation were exploited as key steps. The synthesis was flexible and allowed for the convenient preparation of two analogous natural products glabralide B and denudalide.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308196-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Mary E. Sexton, Ami Okazaki, Zhuowen Yu, Alexis van Venrooy, Jason R. Schmink, William P. Malachowski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, we report the selective mono-γ-arylation of 7-methoxy-4-methylcoumarin under palladium-catalyzed conditions. The Buchwald G3 pre-catalyst in conjunction with either the Xantphos or 〈em〉N〈/em〉-Xantphos ligand proves to be highly reactive, engaging aryl iodides, bromides, chlorides, and triflates to effect the desired transformation. A wide range of functionality is tolerated, including the ability to activate heteroaryl halides in the transformation. The initial scope of aryl halides and limitations of this methodology are presented.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308172-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Fang Fu, Laxman Gurung, Miklos Czaun, Thomas Mathew, G.K. Surya Prakash〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Poly(4-vinyl pyridine) supported bromine/iodine complexes were prepared and probed for 〈em〉ipso〈/em〉-bromination/iodination of arylboronic acids. These solid complexes with catalytic amount of additive are found to be safe and efficient reagent system for the 〈em〉ipso〈/em〉-bromination/iodination. The reaction occurs under mild conditions and tolerates various functional groups resulting in products with high selectivity and yields.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307774-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Sun Woo Lee, Seung Yeob Lee, Seoung Ho Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new chemodosimeter consisting of pyrene and boronic acid (〈strong〉1〈/strong〉) for the detection of Hg〈sup〉2+〈/sup〉 ions is described. The amphiphilic nature of 〈strong〉1〈/strong〉 leads to self-assembly in aqueous solution and the high electron density throughout the aggregated pyrene units provides an outstanding platform for energy and electron transport. Self-assembled 〈strong〉1〈/strong〉 exhibits a selective and sensitive fluorescence response to Hg〈sup〉2+〈/sup〉 ions, where the Hg〈sup〉2+〈/sup〉 ion allows a fast transmetallation of 〈strong〉1〈/strong〉, which drastically reduces its fluorescence. The Stern-Volmer (SV) quenching constant for the fluorescence quenching of self-assembled 〈strong〉1〈/strong〉 by Hg〈sup〉2+〈/sup〉 ions is approximately 1.8 × 10〈sup〉6〈/sup〉 M〈sup〉−1〈/sup〉, and Hg〈sup〉2+〈/sup〉 ions can be sensed with a detection limit of 6.6 × 10〈sup〉−9〈/sup〉 M. In addition, self-assembled 〈strong〉1〈/strong〉 exhibits excellent sensing performance at nano-molar concentration levels for Hg〈sup〉2+〈/sup〉 ion contamination of tap water, fresh water, and seawater.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308056-ga1.jpg" width="415" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Tanja M. Voser, Joshua B. Hayton, Luke P. Robertson, Anthony R. Carroll〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A chemical investigation of the eastern Australian endemic bryozoan 〈em〉Amathia lamourouxi〈/em〉 led to the isolation of two unique betaine molecules, lamouroic acid trifluoroacetate and lamourimidazolinium trifluoroacetate. The structures of these molecules were determined using (+)-HRESIMS, 2D NMR and ECD analyses. The new compounds were screened for antiplasmodial, cytotoxic and antibacterial activity but were inactive at 40 μM. Lamouroic acid trifluoroacetate is structurally related to the ubiquitous marine compound homarine, that has previously been shown to possess feeding deterrent properties, and this suggests that the new compound may also have an ecological role in the bryozoan.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308044-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): Vishal Srivastava, Pravin K. Singh, Praveen P. Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A mild and efficient one-pot visible light-induced method has been developed for the aerobic oxidation of saturated carbon conjugated with pyridine moiety with an important conversion in medicinal and synthetic organic chemistry. This eosin Y based organic transformations, exhibit a novel approach towards site selective functionalization of pyridine with enhance integrity and capability. This novel synthetic route may hold great potential for diverse functionalization of a wide range of pyridine moiety with an economical and sustainable manner.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307981-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 13 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Khairujjaman Laskar, Subham Paul, Utpal Bora〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cellulose catalyzed oxidative hydroxylation of aryl and hetero-arylboronic acids to the corresponding phenols under metal and base free strategy has been demonstrated. The sustainable 〈em〉ipso〈/em〉-hydroxylation takes place using hydrogen peroxide as an oxidant in water under mild condition in shorter period of time. Interestingly, easy recovery and reusability of heterogeneous catalyst without significant loss in catalytic yield makes the protocol environmentally benign.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308019-ga1.jpg" width="250" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): D.G.S. Sudhakar, Ch. Venkata Ramana Reddy, Srinivasa Rao Alapati〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient stereoselective total synthesis of balticolid has been accomplished starting from known aldehyde. The key steps involved in this synthesis are Sharpless asymmetric epoxidation, Wittig olefination, alkylation of 1,3-dithiane and Yamaguchi macrolactonization.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307841-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): Ya-Lan Wang, Chang-Run Guo, Yan Mu, Yun-Liang Lin, Hui-Jiao Yan, Zhi-Wei Wang, Xiao-Jing Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bousigonine A (〈strong〉1〈/strong〉), an unprecedented eburnamine-voaphylline type dimeric indole alkaloid, and Bousigonine B (〈strong〉2〈/strong〉), the first example of eburnamine-eburnamine-aspidospermine type trimeric indole alkaloid were isolated from 〈em〉Bousigonia mekongensis〈/em〉. Their structures were elucidated mainly by spectroscopic analysis and compared to published data. Their preventing high glucose-induced podocyte injury activity were evaluated for the first time, and compound 〈strong〉1〈/strong〉 exhibited significant effect with EC〈sub〉50〈/sub〉 value of 2.5 μM.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307993-ga1.jpg" width="337" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Yuki Miyazawa, Makoto Sugimoto, Ayumi Tanaka-Oda, Hidefumi Makabe〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Syntheses of (+)-goniopypyrone and (+)-goniotriol isolated from 〈em〉Goniothalamus giganteus〈/em〉 were achieved. The key steps involve Pd-catalyzed carbonylation for lactone ring formation and diastereoselective reduction of ynone using the (〈em〉R〈/em〉)-CBS catalyst and borane dimethyl sulfide complex.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307968-ga1.jpg" width="465" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Kakeru Maeda, Ryo Murakami, Fuyuhiko Inagaki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The silver catalyzed 〈em〉7-endo-trig〈/em〉 cyclization of an ene-diol for the formation of 2,2-dimethyloxepane frameworks has been developed. The spirotype dioxabicyclic products were also produced from the diene-diols. In addition, a gold catalyst featuring the Z-ligand also produced similar cyclization reactions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307956-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): Anthony Choi, Iain Coldham〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉1-Methyl-3,4-dihydroquinoxalin-2(1〈em〉H〈/em〉)-one was heated with a range of aldehydes to generate intermediate azomethine ylides which underwent [3 + 2] cycloaddition reactions with 〈em〉N〈/em〉-methyl or 〈em〉N〈/em〉-phenylmaleimide to give substituted tetrahydropyrroloquinoxalinones. Only one (racemic) stereoisomer was formed in each case and the stereochemical outcome was verified by single crystal X-ray analysis. The products from this multicomponent reaction could be oxidised with DDQ to the pyrroloquinoxalinones.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307804-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Kaori Ando, Junichiro Hattori〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A method for one-pot preparation of Julia-Kocienski sulfides and sulfones from alcohols and thiols is reported. A variety of primary alcohols were converted to the corresponding mesylates by methansulfonyl chloride and triethylamine in THF. After the reaction is complete, thiol (〈strong〉1〈/strong〉 or 〈strong〉10〈/strong〉) and either NaH or 〈em〉t〈/em〉-BuOK were added. The Julia-Kocienski sulfides 〈strong〉3〈/strong〉, 〈strong〉9〈/strong〉 and 〈strong〉11〈/strong〉 were prepared by one-pot two steps procedure from alcohols in 76–96% yields (16 examples). Furthermore, after the sulfide formation, the reaction mixture was neutralized by 〈em〉p〈/em〉-toluenesulfonic acid and treated with H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 and ammonium molybdate in EtOH to give the Julia-Kocienski sulfones 〈strong〉4〈/strong〉 in good yields except for 〈em〉trans〈/em〉-2-hexen-1-ol.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307749-ga1.jpg" width="391" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Yang Wang, Kang Liu, Zhi-Xiang Yu, Yanxing Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An attempt to access the fused 7/5 ring of the highly biologically active terpenoid caribenol A by employing intramolecular Pauson-Khand reaction of 1,8-enyne gave bridged 8-5 ring, the type-II Pauson-Khand reaction product. DFT study has been carried out to elucidate this unexpected regioselectivity.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307580-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 32〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 32〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Chen Chen, Jie Ding, Yuebo Wang, Xiaonan Shi, Dequan Jiao, Bolin Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A copper-catalyzed iminohalogenation of unactivated alkenes of γ, δ-unsaturated oxime esters is achieved by using readily available halide salts. Utilizing this protocol, a sequence of structurally diversiform 2-halomethyl pyrrolines are efficiently synthesized and a mechanism involving iminyl radical intermediates, which were initiated by Cu(I) species, was proposed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307579-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 32〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 32〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 17 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Othman Al Musaimi, Ayman El-Faham, Alessandra Basso, Beatriz G. de la Torre, Fernando Albericio〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Due to the hazardous nature of CH〈sub〉2〈/sub〉Cl〈sub〉2〈/sub〉, regulatory authorities have imposed restrictions to minimize or even stop its use. It has therefore become imperative to identify environmentally benign solvents to replace it. Here we report on a bio derived solvent, γ-valerolactone, for the incorporation of the first amino acid onto p-alkoxybenzyl alcohol resin in solid-phase peptide synthesis. Satisfactory loading values (by a spectrophotometric method) were achieved. Furthermore, racemization and dipeptide formation were also checked and found to be acceptable.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308184-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Zhongrui Chen, Maxime Bert, Simon Pascal, Gabriel Canard, Olivier Siri〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The transamination reaction of 2,5-diaminobenzoquinonediimine (QDI) with ethylenediamine gave fluorescent 1,2,3,4-tetrahydropyrazino[2,3-〈em〉g〈/em〉]quinoxaline (〈strong〉1〈/strong〉). When the same reaction was carried out with 〈em〉N,N’〈/em〉-bis(aminoethyl)-1,3-propanediamine, a novel cationic quinoxalinium species (〈strong〉2〈/strong〉) was isolated, which can be further condensed with 〈em〉p〈/em〉-cyanobenzaldehyde to afford a benzimidazolo-fused quinoxaline dye (〈strong〉3〈/strong〉) that is a water-soluble fluorophore in the UV–visible range.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307816-ga1.jpg" width="382" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Saverio Santi, Serena Rossi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Progresses in the design and application of conjugated small molecules, oligomers and polymers have empowered rapid development of organic electronic technology as an alternative to conventional devices. Among the numerous organic electronic materials, benzotrithiophene (BTT)-based oligomers and polymers have recently come in the limelight demonstrating great potential in organic electronics as high performance photovoltaic devices, field-effect transistors, electrochromic materials, high-area capacitors and charge carrier discotic liquid crystals. In this digest, we propose an overview of the organic electronic materials based on BTT isomers, highlighting the structure-performance relationship. The results obtained so far clearly indicate that the BTT isomers are among the most promising building blocks for the development π-extended materials for optoelectronic applications in the near future.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307786-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Sri Venkateswarlu Rayudu, Dipankar Karmakar, Pramod Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient, cost-effective and environmentally benign synthesis of novel tetracyclic bis-isoxazolopyrroloquinoline derivatives has been developed via one-pot four-component reaction of 4-amino-3-methyl-5-styrylisoxazoles, dimedone, aryl glyoxal monohydrates and 5-amino-3-methylisoxazole by employing water as a reaction medium and acetic acid (AcOH) as a green promoter. The advantages of this protocol are environmentally friendly, metal-free, less reaction time, operational simplicity, high yields, broad substrate scope and easy purification. Most significant of all, this method is green.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307828-ga1.jpg" width="450" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Michael Moir, Rochelle Boyd, Hendra Gunosewoyo, Andrew P. Montgomery, Mark Connor, Michael Kassiou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The CB〈sub〉2〈/sub〉 receptor is an attractive target for the treatment of a wide range of diseases and pathological conditions. Compounds that selectively activate the CB〈sub〉2〈/sub〉 receptor are desirable as this avoids CB〈sub〉1〈/sub〉-mediated psychoactive effects. Heteroarylidene-benzamides have demonstrated efficacy as selective CB〈sub〉2〈/sub〉 receptor agonists. We aimed to expand the structure-activity relationship studies of this series of compounds by investigating the heteroaromatic core via the synthesis and 〈em〉in vitro〈/em〉 evaluation of a small library of various heteroaromatic benzamide analogues. As heteroaromatic amides are privileged scaffolds in drug design, methods to synthesise them are of interest. Concise and reliable synthetic strategies were developed to access these novel analogues. The –ylidene-benzamide moiety is shown to be essential for CB activity as all amide derivatives exhibit no functional activity at either CB〈sub〉2〈/sub〉 or CB〈sub〉1〈/sub〉 receptors.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The synthesis of a small library of heteroaromatic benzamides as potential cannabinoid type 2 receptor agonists is described.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307762-ga1.jpg" width="378" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 34〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Luana A. Pachechne, Vinicius F. Pereira, Guilherme M. Martins, Edmar Martendal, Fernando R. Xavier, Samuel R. Mendes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A general method for the synthesis of 1,2,3,4-tetrasubstituted pyrroles by [NMPH]CH〈sub〉3〈/sub〉SO〈sub〉3〈/sub〉 is reported. A full factorial design was performed in order to obtain a more robust and statistically correct optimum condition. The products were obtained in moderate to excellent yields. The developed methodology is very simple, cost-effective, and applicable for tri- and tetra-component reactions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308007-ga1.jpg" width="453" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Yunze Li, Min Rao, Zhenwei Fan, Baoyi Nian, Yaofeng Yuan, Jiajia Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient method for visible-light-induced perfluoroalkylaion of quinolin-4-ol has been reported. In the presence of 〈em〉t〈/em〉-BuONa and perfluoroalkyl iodide, quinolin-4-ol underwent C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H perfluoroalkylation under the irradiation of green light. Mechanistic studies demonstrated that visible-light promoted intermolecular charge transfer within the transient electron donor-acceptor complex in the absence of any photocatalysts.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308032-ga1.jpg" width="231" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Kuang Xu, Xuan Zhang, Jing Wei Chen, Yan Shen, Nan Jiang, Ren Xiang Tan, Rui Hua Jiao, Hui Ming Ge〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three new pimarane-type diterpenoids, along with two known compounds, were isolated from an endophytic fungus 〈em〉Phomopsis〈/em〉 sp. S12. Their structures were determined by comprehensive analyses of HRESIMS, NMR, CD, as well as single-crystal X-ray diffractions. Compound 〈strong〉3〈/strong〉 exhibited anti-inflammatory activity against the production of IL-1β and IL-6 induced by lipopolysaccharide (LPS) in macrophages. A putative biosynthetic pathway for compounds 〈strong〉1〈/strong〉–〈strong〉5〈/strong〉 were also proposed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308020-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Woo Cheol Jang, Dong Wook Hwang, Jeong Hoon Seo, Haye Min Ko〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A facile method for the transition-metal-free diarylation of isocyanates with arynes in the presence of cesium fluoride has been developed, which affords functionalized diaryl amines in moderate to excellent yields. This reaction has good functional group tolerance and provides excellent regioselectivity by utilizing a methoxy-substituted aryne precursor.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307750-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): Thidarat Chalothorn, Vatcharin Rukachaisirikul, Souwalak Phongpaichit, Sakawrat Pannara, Chittreeya Tansakul〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Synthesis of the antibacterial emodin was improved using Friedel-Crafts acylation as a key step leading to 37% overall yield. In addition, 21 analogues were synthesized by structural modification of the hydroxyl and methyl groups, as well as the aromatic ring of emodin. Antibacterial activity against methicillin-resistant 〈em〉Staphylococcus aureus〈/em〉 (MRSA) and cytotoxicity against noncancerous Vero cells were evaluated. A structure-activity relationship (SAR) study indicated that the hydroxyl groups and the methyl group in the emodin skeleton were crucial for anti-MRSA activity. Furthermore, the presence of an iodine atom or ethylamino group on the aromatic ring enhanced the anti-MRSA activity with higher selectivity indices, while derivatives containing bromine, chlorine atoms or quaternary ammonium salt were as active as emodin. The quaternary ammonium group on the aromatic ring also led to non-cytotoxicity against Vero cells.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307610-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Raul F. Velasco, César Guerrero, Gloria Fra, Alejandra Moure, Juan Miguel-Siles, Maria Teresa Quesada-Campos, Jose Ramon Ruiz-Gomez, Ian H. Gilbert, Michael G. Thomas, Timothy J. Miles〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉During the course of a research program aimed at identifying novel antileishmanial compounds, a multi-gram synthesis of 〈em〉N〈/em〉-(〈em〉trans〈/em〉-4-((4-methoxy-3-((〈em〉R〈/em〉)-3-methylmorpholino)-1〈em〉H〈/em〉-pyrazolo[3,4-〈em〉d〈/em〉]pyrimidin-6-yl)amino)cyclohexyl)-2-methylpropane-1-sulfonamide (〈strong〉(〈em〉R〈/em〉)-1〈/strong〉) was required. This letter describes optimisation of the reaction conditions and protecting group strategy for a key Buchwald-Hartwig coupling, delivering the required quantities of 〈strong〉(〈em〉R〈/em〉)-1〈/strong〉, as well as further compounds in the series.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919303065-ga1.jpg" width="481" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 18 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 16〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Dolores Santa María, Rosa M. Claramunt, M. Carmen Torralba, M. Rosario Torres, José Elguero〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synthesis and characterization of a new 24-membered tetramide macrocycle (〈strong〉6〈/strong〉) related to Leigh's macrocycles and catenanes is reported. The replacement of 〈em〉p〈/em〉-xylylenediamine (Leigh) by 〈em〉m〈/em〉-xylylenediamine (this work) strongly modifies the geometry and properties of the new macrocycle. NMR spectroscopy (in DMSO-〈em〉d〈sub〉6〈/sub〉〈/em〉 solution) and X-ray crystallography have been used to characterize compound 〈strong〉6〈/strong〉. The structural features in the crystal (conformational aspects and H-bonding) have been discussed comparatively to two similar macrocycles NEWHIJ and UJUNOC.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040391930303X-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Shuai-Shuai Sun, Junyou Chen, Rui Zhao, Donald Bierer, Jun Wang, Ge-Min Fang, Yi-Ming Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Solid-phase incorporation of diaminodiacids is one of the most effective approaches for synthesis of peptide disulfide bond mimics. One of a limitation of current diaminodiacid toolbox is that only four-atom linkage mimics are available that may not fully meet the activity optimization requirement. In this work, we developed a new diaminodiacid that contains a five-atom thioether (C–C–S–C–C) bridge for the first time. With this diaminodiacid in hand, we successfully obtained oxytocin containing new disulfide bond mimic by solid phase peptide synthesis.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919302904-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Weiwei Zhao, Xiangqing Feng, Jing Yang, Haifeng Du〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Optically active β-amino acids and their derivatives are very useful building blocks in synthetic and medicinal chemistry. The catalytic asymmetric reduction of β-enamino esters is one of the most efficient approaches for their synthesis. Ammonia borane with low molecular weight, high hydrogen capacity, and good stability, is an ideal hydrogen source for the transfer hydrogenation. However, only a few successful examples have been reported for the asymmetric reduction with ammonia borane. In this work, an asymmetric metal-free transfer hydrogenation of β-〈em〉N〈/em〉-substituted enamino esters with ammoinia borane was successfully realized by using a frustrated Lewis pair of Piers’ borane and (〈em〉S〈/em〉)-〈em〉tert〈/em〉-butylsulfinamide as a chiral catalyst. A variety of β-amino acid derivatives were obtained in 51−90% yields with up to 91% ee.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉With ammonia borane as hydrogen source, an asymmetric transfer hydrogenation of β-〈em〉N〈/em〉-substituted enamino esters was successfully realized to give β-amino acid derivatives in 51−90% yields with up to 91% ee by using a combination of Piers’ borane and (〈em〉S〈/em〉)-〈em〉tert〈/em〉-butylsulfinamide as a chiral catalyst.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919302898-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Shanshan Chen, Shi-Hang Xie, Cheng-Ying Ai, Xiu-Li Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A palladium catalyzed oxidative cross-coupling reaction between terminal alkynes and acrylates was developed. In the presence of palladium catalyst and copper(II) acetate as oxidant, the cross dimerization products with were formed. This protocol provides a novel method to construct the tetrasubstituted functionalized alkenes.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919302874-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Tao Yang, Xian-Rong Song, Ren Li, Fengyan Jin, Yuxing Zhang, Jiang Bai, Ruchun Yang, Haixin Ding, Qiang Xiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A metal-free, Brønsted acid-mediated cascade cyclization of 2-propynolphenols for efficient synthesis of various 4-thiocyanated 2〈em〉H〈/em〉-chromenes is developed by using KSCN as the thiocyanated source. This reaction was characterized by readily prepared starting materials, bearing good functional group tolerance and excellent yields. Moreover, the obtained 4-thiocyanated 2〈em〉H〈/em〉-chromenes could be further derivated to potential bioacitve and pharmaceutical molecules.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919303089-ga1.jpg" width="470" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Noel McLaughlin, Colm Duffy, Francesco Alletto, Andrea Ravelli, Stefano Lancianesi, Malachi Gillick-Healy, Mauro F.A. Adamo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The diastereoselective reduction of γ-keto-sulfonates to afford α,γ-substituted γ-hydroxy sulfonates has been investigated. Herein we report the first example of a diastereoselective carbonyl reduction whereby hydride attack is directed 〈em〉via〈/em〉 chelation of a neighbouring sulfonate group to a boron atom, thus affording prevalently 〈em〉trans〈/em〉 γ-hydroxy sulfonates.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919303041-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Zhuo-Wei Xu, Wen-Yi Xu, Xiao-Jun Pei, Fei Tang, Yi-Si Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple catalyst- and additive-free method for the N-formylation of amines has been developed. The advantages of this protocol include a wide range of functional group tolerance, high efficiency and a lack of required extra promoters under mild conditions. This convenient strategy will provide a facile synthesis towards N-formamide natural products and pharmaceutical derivatives. A mechanism that involves difluorocarbene is proposed for this reaction.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919303090-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Yajuan Zhang, Min Tong, Qian Gao, Panke Zhang, Senmiao Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chiral α-aminosilane and its derivatives have found potential applications in pharmaceuticals. Yet there are rare examples have been reported for the synthesis of these molecules. Herein we report a catalytic asymmetric conjugate silylation reactions of β-amido-acrylonitriles and β-amido-acrylates for the first time in the presence of catalytic amount of chiral N-heterocyclic carbene (NHC)/Copper(I) complex. A variety of functionalized chiral α-aminosilanes were obtained at room temperature in good yields with high enantioselectivities in the presence of NHC (10 mol%), CuCl (10 mol%), NaOtBu or NaOMe (20 mol%), and MeOH (2 equivalents).〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919303107-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Yaqun Dong, Song Sun, Jin-tao Yu, Jiang Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A rhodium-catalyzed direct C−H sulfonamidation and amidation of C-7 position of indolines by simple and commercially available arylsulfonamides and trifluoroacetamide has been developed, affording a series of N-arylsulfonamides and N-aryltrifluoroacetamides in moderate to excellent yields, respectively. Notably, this catalytic system is highly convenient on mmol scale.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919303077-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 18 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 16〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 18 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 16〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 18 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 16〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Mugada Sugunakara Rao, Subhankar Sarkar, Sahid Hussain〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple and efficient one-pot two-step synthesis of substituted 3-aminoarylquinolines has been achieved from 2-nitrobenzaldehyde and indoles under microwave irradiation. Firstly 2-nitrobenzaldehydes is reduced to 2-aminobenzaldehyde in situ by commonly used chemo selective reductant SnCl〈sub〉2〈/sub〉 followed by condensation of indole. The acidic nature of the resultant reaction mixture due to SnCl〈sub〉2〈/sub〉 helps in the condensation and facile ring opening of indole leading to the formation of 3-aminoarylquinoline derivatives in good to moderate yields.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919302643-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Haihang Zhao, Ling Li, Yuan Cao, Guidong Gong, Yangyang Zhou, XingXing Gao, Lin Pu, Gang Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A BINAM-based compound (〈em〉R〈/em〉)-〈strong〉1〈/strong〉 is found to show significant fluorescence enhancement in the presence of Lys in aqueous solution (1%DMF). This probe achieves highly selective fluorescent recognition of Lys even in the presence of other natural amino acids. It can be used as a sensitive as well as selective fluorescent probe for Lys. The mechanism for the interaction of (〈em〉R〈/em〉)-〈strong〉1〈/strong〉 with Lys was studied by NMR and HRMS.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉〈strong〉Fluorescent sensing〈/strong〉: A BINAM-based compound shows significant fluorescence enhancement toward Lys in aqueous solution through a nucleophilic substitution reaction.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919302928-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Ye-Fu Zhu, Bo-Le Wei, Jiao-Jiao Wei, Wen-Qiong Wang, Wei-Bin Song, Li-Jiang Xuan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A palladium-catalyzed oxidative dehydrogenation reaction in the presence of AMS and base to synthesize pyrazolones and pyrazoles was identified. This method can be utilized to a wide range of substrates, operates under mild react conditions and can give high yields. We believe it could be used as an alternative protocol for the classical dehydrogenation reactions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919302916-ga1.jpg" width="468" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Yan Xiao, Shuo Wang, Jianyu Liu, Hui Zhang, Yongnan Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel protocol for the C–H methylthiolation of 2-phenyl pyridines using DMSO as the methylthio source and an amino acid ligand is described. This simple procedure requires neither an oxidant nor additional solvent. The developed protocol tolerates a wide range of functional groups including methyl, methoxy, fluoro, chloro, and in particular the formyl group. This new strategy is highly regioselective and provides aryl methyl sulfides from 2-phenyl pyridines in moderate to good yields.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919303053-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Ren Li, Fengyan Jin, Xian-Rong Song, Tao Yang, Haixin Ding, Ruchun Yang, Qiang Xiao, Yong-Min Liang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel and efficient 〈em〉p〈/em〉-TsOH-promoted cascade cyclization of 2-propynolphenols is developed to give 4-tosyloxy-2〈em〉H〈/em〉-chromenes in moderate to efficient yields. It is noted that 〈em〉p〈/em〉-TsOH acts not only as a promoter in this reaction, and also as the sulfonate source. Importantly, the obtained 4-tosyloxy-2〈em〉H〈/em〉-chromenes can be used as versatile intermediates for the synthesis of various functionalized compounds through diverse metal-catalyzed cross-coupling reactions. Moreover, this method can be enlarged to gram scale.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918314540-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 7 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 6〈/p〉 〈p〉Author(s): Peiran Chen, Yajun Ding, Saisai Guo, Xiaoying Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉By using Hf(OTf)〈sub〉4〈/sub〉 as the catalyst, a series of 2,3-unsaturated-〈em〉Se〈/em〉-glucosides have been synthesized for the first time from tri-〈em〉O〈/em〉-acetyl-〈span〉d〈/span〉-glucal, 2,4,6-tri-〈em〉O〈/em〉-benzyl-〈span〉d〈/span〉-glucal, 3,4-di-〈em〉O〈/em〉-acetyl-〈span〉l〈/span〉-rhamnal and ((2〈em〉R〈/em〉,3〈em〉S〈/em〉)-3-acetoxy-2,3-dihydrofuran-2-yl) methyl acetate with PhSeH or alkyl(aryl) hydroselenides as the nucleophile in good yield and high anomeric selectivity.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919300024-ga1.jpg" width="256" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 31 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 5〈/p〉 〈p〉Author(s): Sayan Pramanik, Suvendu Maity, Prasanta Ghosh, Chhanda Mukhopadhyay〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An acid-promoted multicomponent reaction for the direct C(sp〈sup〉3〈/sup〉)〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N bond formation was achieved through intermolecular allylic amidation in a one-pot operation to synthesize 7-acetamido tetrahydroindole derivatives from simple and readily available arylglyoxal monohydrates, acetonitriles, and enamines of 5,5-dimethyl-1,3-cyclohexadione (dimedone) has been developed. Here acetonitrile acts both as solvent and reagent. These tetahydroindole derivatives are formed through domino condensation of the enamines and arylglyoxals followed by annulation and allylic amidation.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315260-ga1.jpg" width="402" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 21 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 8〈/p〉 〈p〉Author(s): Evgeniya Podyacheva, Ekaterina Kuchuk, Denis Chusov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉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-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.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315296-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Sen Zhao, Hang Wang, Shaofa Sun, Haibing Guo, Zhiyu Chen, Jian Wang, Lu Wang, Steven Liang, Gangqiang Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉2-Isoxazolines were synthesized efficiently from a formal [4+1] cycloaddition of nitrosoalkenes and sulfur ylides, which were generated 〈em〉in situ〈/em〉 from α-haloketone oximes and dimethyl sulfonium salts. This approach provides a new method to synthesize a range of 2-isoxazolines in high yields and high regioselectivity.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉2-Isoxazolines were synthesized efficiently at ambient temperature from a formal [4+1] cycloaddition of nitrosoalkenes and sulfur ylides, which were generated 〈em〉in situ〈/em〉 from α-haloketone oximes and dimethyl sulfonium salts. This approach provides a new method to synthesize a range of 2-isoxazolines in high yields and high regioselectivity.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040391831520X-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Nasim Tajaddini, Mahdiyeh Talebizadeh, Mohammad Anary-Abbasinejad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient one-pot method for the synthesis of new substituted cylopentenone derivatives is described via reaction of arylglyoxals and acetylacetone with aliphatic amines. This reaction was carried out in aqueous media in the absence of any catalyst or promoter to produce substituted cylopentenone in high yield.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315077-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Tanay Ghoshal, Vishal Nagar, Adilakshmi Vutla, Sharadsrikar Kotturi, Sasikumar Kuttappan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient single step process for the construction of pharmaceutically relevant substituted aminobenzoxazoles have been described in this report. Various electrodes and electrolytes combinations have been carried out to harvest optimum coupling results. The presented C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N bond formation reaction methodology has applied for the synthesis of biologically active compounds. This methodology saves reaction steps over traditional functionalization reactions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315053-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Laize A.F. Andrade, Josué M. Silla, Matheus P. Freitas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Conformational stabilities of 2-halocyclohexane-1,3-diones are strongly affected by steric and dipolar effects involving the carbonyl groups and the equatorial halogen. However, 2-fluorocyclohexane-1,3-dione has been found to be mostly equatorial, because of electron delocalization in this conformer that overcomes repulsive interactions, while the other halogen derivatives perform as expected.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315065-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 7 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 6〈/p〉 〈p〉Author(s): Takahiro Tamura, Jun-ichi Tamura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉〈em〉O〈/em〉-mannosyl glycan is a pivotal glycan part of α-dystroglycan, which serves as a transmembrane linker connecting the intracellular cytoskeleton and extracellular matrix, such as laminin in skeletal muscle. We synthesized β-〈span〉d〈/span〉-Xyl-(1–4)-〈span〉d〈/span〉-Rbo-5P (〈strong〉1〈/strong〉), β-〈span〉d〈/span〉-Xyl-(1–4)-〈span〉d〈/span〉-Rbo (〈strong〉2〈/strong〉), and β-〈span〉d〈/span〉-Xyl-(1–4)-〈span〉d〈/span〉-Rbo-5P1-〈span〉d〈/span〉-Rbo (〈strong〉3〈/strong〉), partial structures of 〈em〉O〈/em〉-mannosyl glycan, in regio- and stereo-controlled manners, and demonstrated compatibility with the natural product.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315259-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Takafumi Saito, Kenshu Fujiwara, Yoshihiko Kondo, Uichi Akiba, Takanori Suzuki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synthesis of the cyclohexene segment of portimine, a marine cytotoxin from the dinoflagellate 〈em〉Vulcanodinium rugosum〈/em〉, was achieved. The route includes an acylation/aldol reaction from 3-ethoxycyclohex-2-enone to create the C3 center, the 1,4-addition of a vinyl group at C16, the diastereoselective dihydroxylation of the vinyl group to generate the C15 center, a vinylation/dehydration sequence to set up the diene moiety, and stepwise installation of the amino-group-substituted C1 unit.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315211-ga1.jpg" width="475" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Guangrong Meng, Lazaros Kakalis, Steven P. Nolan, Michal Szostak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The σ-donor properties of NHC ligands (NHC = N-heterocyclic carbene) are crucial in controlling their interaction with transition metals, and as a consequence, to determine the selectivity and reactivity of NHCs in transition-metal-catalysis. Herein, we report a simple NMR method for estimating the σ-donor properties of NHC ligands based on a straightforward 〈sup〉1〈/sup〉H NMR measurement of ligand precursors. We present evaluation of σ-donating properties for a range of NHC ligands varied by structure and electronics that are relevant to transition-metal-catalysis. We expect that the simple measurement of σ-donating properties of NHCs, together with the known methods for evaluating sterics and π-backbonding, will enhance the understanding of the properties of NHCs in transition-metal-catalysis.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315107-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Mykola Kolotylo, Volodymyr Holovatiuk, Julia Bondareva, Oleg Lukin, Vladimir Rozhkov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synthesis of dendrimers and a chlorosulfo-dendron possessing a unique combination of 1 → 2 and 1 → 4 branching types is described. The procedure consists of a two-step preparation of 3,5-dinitrobenzene-1-sulfonyl chloride, which was used for the persulfonylation of 〈em〉p〈/em〉-toluidine and 4-(benzylthio)aniline. The obtained tetranitro compounds were reduced to the corresponding tetraamines. The latter were decorated with eight 4-toluene sulfonyl groups each to furnish the corresponding dendrimers. Oxidation of the dendrimer possessing a 4-(benzylthio)phenylene core with 〈em〉N〈/em〉-chlorosuccinimide resulted in the formation of a dendron with a sulfonyl chloride functionality at the focal point.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040391831503X-ga1.jpg" width="398" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Bakhtar Ullah, Yuli Zhou, Jingwen Chen, Zongbi Bao, Yiwen Yang, Qiwei Yang, Qilong Ren, Zhiguo Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thiourea itself has been introduced as a mild and efficient organocatalyst for the oxidative α -cyanation of 〈em〉N〈/em〉-aryltetrahydroisoquinolines (THIQs) with trimethylsilyl cyanide (TMSCN), giving the corresponding products in good to excellent yields. Experimental investigations demonstrated that thiourea acts as a radical initiator by abstracting hydroxyl radical (〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/rad"〉OH) from 〈em〉tert〈/em〉-butyl hydroperoxide (TBHP) directly instead of non-covalent hydrogen bondings (H-bondings) activation. The use of thiourea as a radical initiator offers a new avenue for innovative chemical transformations in organocatalyzed radical chemistry.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315016-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 31 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 5〈/p〉 〈p〉Author(s): Kazumasa Kon, Yoshihito Kohari, Miki Murata〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The development of unnatural tripeptides as highly enantioselective organocatalysts for the asymmetric aldol reaction of isatins was achieved. H-Pro-Gly-〈span〉d〈/span〉-Ala-OH with the 〈span〉d〈/span〉-alanine residue as the C-terminal amino acid residue expressed the best enantioselectivity. The H-Pro-Gly-〈span〉d〈/span〉-Ala-OH-catalyzed reaction of isatins gave various aldol adducts with up to 93% yield and up to 97% ee. Investigation of the transition state via DFT calculation revealed that high optical purity was realized by the 〈span〉d〈/span〉-alanine controlled steric environment.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315004-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 24 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 4〈/p〉 〈p〉Author(s): Guillaume Laconde, Muriel Amblard, Jean Martinez〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient method for the synthesis of 〈em〉N〈/em〉-acyl-benzotriazoles from a wide variety of protected amino acids, as well as from compounds frequently used in drug discovery such as biotin and 〈em〉N〈/em〉-Fmoc polyethylene glycol, has been developed. The reaction of carboxylic acid derivatives with benzotriazole in the presence of T3P® yielded the corresponding 〈em〉N〈/em〉-acyl-benzotriazoles, which were obtained in high purity following a simple work-up procedure, in most cases 〈em〉via〈/em〉 precipitation of the desired product in water.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918314989-ga1.jpg" width="468" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 31 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 5〈/p〉 〈p〉Author(s): Xingquan Xiong, Chao Yi, Xu Liao, Shilin Lai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of 5-substituted-1〈em〉H〈/em〉-tetrazoles have been efficiently synthesized in moderate to excellent yields (68–90%) under mild reaction conditions by combining aryl aldehydes, hydroxylamine hydrochloride with sodium azide in the presence of catalytic amount of Cu(OAc)〈sub〉2〈/sub〉 in deep eutectic solvent (DES). The new synthetic method has many advantages, such as high conversion, green reaction medium, easy work-up, low cost, and environment friendly.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918314795-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 31 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 5〈/p〉 〈p〉Author(s): Deboprosad Mondal, Haichan Niu, Kevin G. Pinney〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Benzosuberene analogues (〈strong〉1〈/strong〉 and 〈strong〉2〈/strong〉) and dihydronaphthalene analogues (〈strong〉3〈/strong〉 and 〈strong〉4〈/strong〉) function as potent inhibitors of tubulin polymerization, demonstrate pronounced cytotoxicity (low nM to pM range) against human cancer cell lines, and are promising vascular disrupting agents (VDAs). As such, these compounds represent lead anticancer agents with potential translatability towards the clinic. Methodology previously established by us (and others) facilitated synthetic access to a variety of structural and functional group modifications necessary to explore structure activity relationship considerations directed towards the development of these (and related) molecules as potential therapeutic agents. During the course of these studies it became apparent that the availability of synthetic methodology to facilitate direct conversion of the phenolic-based compounds to their corresponding aniline congeners would be beneficial. Accordingly, modified synthetic routes toward these target phenols (benzosuberene 〈strong〉1〈/strong〉 and dihydronaphthalene 〈strong〉3〈/strong〉) were developed in order to improve scalability and overall yield [45-57% (〈strong〉1〈/strong〉) and 32% (〈strong〉3〈/strong〉)]. Moreover, benzosuberene-based phenolic analogue 〈strong〉1〈/strong〉 and separately dihydronaphthalene-based phenolic analogue 〈strong〉3〈/strong〉 were successfully converted into their corresponding aniline analogues 〈strong〉2〈/strong〉 and 〈strong〉4〈/strong〉 in good yield (〉60% over three steps) using a palladium catalyzed amination reaction.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918314758-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 7 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 6〈/p〉 〈p〉Author(s): K. Jones M. Swapnaja, Satyanarayana Yennam, Murthy Chavali〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉〈strong〉“〈/strong〉A series of novel spirobiisoxazoline dibenzoquinone derivatives were synthesized starting from 2,5-dimethoxybenzaldehyde in a six-step synthetic sequence”. The key step [3 + 2] double 1,3-dipolar cycloaddition of oxime chloride with allenoate was performed under mild reaction conditions using sodium carbonate at ambient temperature. This is the first innovative synthesis of Spirobiisoxazoline Dibenzoquinone system where quinone ring is alkylated to isoxazoline moiety.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403918315272-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉