Direct Sulfide-Catalyzed Enantioselective Cyclopropanations of Electron-Deficient Dienes and Bromides
作者:Qing-Zhu Li、Xiang Zhang、Rong Zeng、Qing-Song Dai、Yue Liu、Xu-Dong Shen、Hai-Jun Leng、Kai-Chuan Yang、Jun-Long Li
DOI:10.1021/acs.orglett.8b01537
日期:2018.6.15
A catalytic highly regioselective, diastereoselective, and enantioselective cyclopropanation of electron-deficient dienes and bromides via direct sulfide organocatalysis is reported. A variety of vinylcyclopropanes featuring a quaternary chiral center were synthesized in up to 99% yield and up to 98:2 enantiomeric ratio (er). These products could be facilely transformed to various interesting molecules
modular method for the synthesis of (Z)-3-[amino(phenyl/methyl)methylidene]-1,3-dihydro-2H-indol-2-ones starting from easily available 3-bromooxindoles or (2-oxoindolin-3-yl)triflate and thioacetamides or thiobenzamides is described. A series of 49 compounds, several of which have previously been shown to possess significant tyrosin kinase inhibiting activity, was prepared in yields varying mostly from
Ammonium ylides have a long history in organic synthesis, but their application in asymmetric catalysis is still underdeveloped in regard to both substrate scope and reaction pathways compared with phosphorus and sulfur ylides. Here a previously unreported asymmetric [4 + 1] annulationreaction of 3-bromooxindoles and electron-deficient 1-azadienes has been developed through ammonium ylide catalysis
3-Bromooxindoles as nucleophiles in asymmetric organocatalytic Mannich reactions with N-Ts-imines
作者:Jianhao Li、Taiping Du、Gang Zhang、Yungui Peng
DOI:10.1039/c2cc38475b
日期:——
A direct asymmetric Mannich reaction of N-unprotected 3-bromooxindoles with N-Ts-imines catalyzed by bifunctional thiourea derivedfrom 2-substituted cinchona alkaloid was developed. Products with vicinal chiral tertiary and brominated quaternary stereogenic centers were achieved in excellent diastereo- and enantioselectivity (up to 99 : 1 dr, 99% ee).
Formation of 3-[amino(aryl)-methylidene]-1,3-dihydro-2 H -indol-2-ones involving ring transformation of 2-aryl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazoles
starting 3-bromooxindole completely prevents formation of thiazoles. The prepared thiazoles 3b-f are unstable in solution and they undergo slow ringtransformation to 2b-f. The rate limiting step of this rearrangement involves cleavage of an intermediary thiirane ring, which is slowed down by electron-withdrawing substituents on the thioamide (ρ = −1.15).