Asymmetric Organocatalysis in the Synthesis of Pyrrolidine Derivatives­ Bearing a Benzofuran-3(2H)-one Scaffold

Abstract

A new enantio- and diastereoselective approach to pyrrolidine derivatives bearing a benzofuran-3(2<i>H</i>)-one scaffold is reported. The approach, based on the [3+2] cycloaddition between 2-arylidenebenzofuran-3(2<i>H</i>)-ones and imines derived from salicylaldehyde and diethyl aminomalonates, benefits from broad substrate scope, high chemical and stereochemical efficiency, and operational simplicity. Notably, simple and readily available quinine is employed as the catalyst of the reaction. Target products bearing two biologically relevant heterocyclic moieties and three adjacent stereogenic centers with one being quaternary have been obtained in excellent yields and in a highly stereoselective manner.