Asymmetric Michael Addition Reactions between 3-Substituted Benzofuran-2(3H)-ones and 1,1-Bis(phenylsulfonyl)ethylene Catalyzed by Bifunctional Catalysts Containing Tertiary Amine and Thiourea Groups
Highly enantioselective catalytic conjugate additions of 3-substituted benzofuran-2(3H)-ones to 1,1-bis(phenylsulfonyl)ethylene in the presence of catalysts based on Cinchona alkaloids and containing tertiaryamine and thiourea groups have been developed. Good to excellent stereoselectivities (up to 99 % ee) could be achieved. An interesting effect of substituent positions on stereoselectivities was
Organocatalytic Asymmetric Branching Sequence of MBH Carbonates: Access to Chiral Benzofuran-2(3<i>H</i>)-one Derivatives with Three Stereocenters
作者:Chuanle Zhu、Lijun Yang、Jing Nie、Yan Zheng、Junan Ma
DOI:10.1002/cjoc.201200809
日期:2012.11
An organocatalyticasymmetricbranchingsequence was realized in the presence of 10 mol% of (DHQD)2AQN, affording the sequential products with three stereocentres, including two quaternary carbon centres, in 47%–79% yields with 85%–99% ee.
An efficient amination reaction of 3-substituted benzofuran-2(3H)-ones promoted by cesium carbonate was developed. A putative mechanism involving a single-electron-transfer event was proposed, which represents a new reactivity for benzofuran-2(3H)-ones.