Asymmetric Conjugate Addition of Oxindoles to 2-Chloroacrylonitrile: A Highly Effective Organocatalytic Strategy for Simultaneous Construction of 1,3-Nonadjacent Stereocenters Leading to Chiral Pyrroloindolines

摘要

Chiral pyrroloindoles: A highly enantioselective catalytic conjugate addition of 3-substituted oxindoles with 2-chloroacrylonitrile has been developed with a readily accessible alkyl bifunctional tertiary amine thiourea catalyst. Excellent stereoselectivity of up to 30:1 diastereomeric ratio and 99 % enantiomeric excess was achieved. The obtained Michael products could be easily converted to chiral pyrroloindole structures, which are widely distributed in natural indole alkaloids (see scheme).