An unprecedented strategy to access highly enantioenriched dihydropyrazoles is described. It involves formal [4+1] cycloadditions of in situ-derived azoalkenes and sulfurylides catalyzed by a chiral copper/Tol-BINAP complex. A variety of synthetically and biologically important dihydropyrazoles have been obtained with high enantioselectivities (up to 97:3 er) in good yields (83-97%).
Substrate-controlled reactions have been developed for the synthesis of spirocyclopropylpyrazolones and bicyclic 4,5-dihydropyrazoles from 1,2-diaza-1,3-dienes and sulfur ylides. These protocols were carried out under mild reaction conditions without any additives in generally moderate to good yields. Plausible mechanisms for the transformations were proposed.
Highly Diastereoselective Synthesis of Trifluoromethyl Indolines by Interceptive Benzylic Decarboxylative Cycloaddition of Nonvinyl, Trifluoromethyl Benzoxazinanones with Sulfur Ylides under Palladium Catalysis
diastereoselective synthesis of trifluoromethyl-substituted indolines under palladium catalysis is disclosed. The reaction proceeds by interceptive decarboxylative benzylic cycloaddition (IDBC) of nonvinyl, trifluoromethyl benzoxazinanones with sulfur ylides. The palladium−π-benzyl zwitterionic intermediates are suggested for this transformation, and this would be the first example of an IDBC reaction.
A cascade deprotonation/intramolecular aldol reaction of α-carbonyl sulfonium ylides with 2-mercaptoindole-3-carbaldehydes and 2-mercaptobenzaldehydes to access thieno[2,3-<i>b</i>]indoles and benzothiophenes
The first catalyst-free cascade deprotonation/intramolecular aldol reaction of α-carbonyl sulfoniumylides with 2-mercaptoindole-3-carbaldehydes and 2-mercaptobenzaldehydes was developed. A series of thieno[2,3-b]indoles and benzothiophenes were smoothly obtained in high to excellent yields. The salient features of the protocol include catalyst-free conditions, an environment-friendly solvent, broad
开发了第一个无催化剂的α-羰基sulf烷基化物与2-巯基吲哚-3-甲醛和2-巯基苯甲醛的级联去质子/分子内羟醛反应。可以高收率或优异收率顺利获得一系列噻吩并[2,3- b ]吲哚和苯并噻吩。该方案的显着特征包括无催化剂条件,环境友好的溶剂,广泛的底物范围和大规模合成。
Diastereoselective Synthesis of 1,3-Diyne-Tethered Trifluoromethylcyclopropanes through a Sulfur Ylide Mediated Cyclopropanation/DBU-Mediated Epimerization Sequence
作者:Guo-Shu Chen、Xiao-Xue Yan、Shu-Jie Chen、Xiang-Yu Mao、Zhao-Dong Li、Yun-Lin Liu
DOI:10.1021/acs.joc.0c00162
日期:2020.5.15
A one-potsynthesis of 1,3-diyne-tethered trifluoromethylcyclopropanes startingfrom 2-CF3-3,5-diyne-1-enes and sulfur ylides via a sulfur ylide mediated cyclopropanation and a DBU-mediated epimerization sequence is described in this work. This process is highly diastereoselective with broad substrate scope. Moreover, a series of synthetic transformations based on the diyne moieties were conducted