A newly developed chiral imidazole nucleophilic catalyst, Acyloxy-DPI, was readily prepared and successfully applied to the enantioselective Black rearrangement with up to 88% ee for a wide range of substrates possessing different substituted groups. A plausible mechanism for the high enantioselectivity was proposed.
enantioselective C-acylation of 3-substituted benzofuran-2(3H)-ones (with up to 97% ee) was developed using a chiral bicyclic imidazole catalyst OAc-DPI and an achiral tertiary amine additive DIPEA. The reaction...
Transition-Metal Free Oxidative Alkynylation of 2-Oxindoles with Ethynylbenziodoxolone (EBX) Reagents
作者:Avishek Roy、Mrinal Kanti Das、Saikat Chaudhuri、Alakesh Bisai
DOI:10.1021/acs.joc.7b02797
日期:2018.1.5
We report an efficient direct alkynylations of 3-alkyl/aryl 2-oxindoles employing ethynyl-1,2-benziodoxol-3(1H)-one (EBX) to afford a wide variety of 3-alkynyl-3-alkyl/aryl 2-oxindole under transition-metal free condition. In addition to activated carbonyl compounds viz. 2-oxindole-3-alkylcarboxylates, this direct alkynylations protocol works efficiently on 3-alkyl/aryl 2-oxindols as well thereby widening
Enantioselective synthesis of Benzofurans bearing adjacent quaternary and tertiary carbon stereocenters by Organocatalytic asymmetric Michael addition of 3-methylbenzofuran −2(3H)-ones to azadienes
An enantioselective Michael addition of 3-methylbenzofuran-2(3H)-ones to azadienes catalyzed by an L-tert- leucine derived squaramide catalyst was developed, by which a variety of benzofuranones bearing adjacentquaternary and tertiary carbon centers were obtained in high yields (up to 98%) with moderate to excellent diastereoselectivities (up to 97:3) and enantioselectivities (up to 97%).