title: The enantioselective Birch-Cope sequence for the synthesis of carbocyclic quaternary stereocenters. Application to the synthesis of (+)-mesembrine.
abstract: A synthetic technique for generating carbocyclic quaternary stereocenters with exceptionally high levels of enantioselectivity is described. A sequence of three reactions, enantioselective Birch reduction-allylation, enol ether hydrolysis, and Cope rearrangement, is used to stereoselectively generate chiral quaternary centers on a 2-cyclohexen-1-one ring. The products of the sequence are 4,4-disubstituted-2-carboxamide-2-cyclohexen-1-one structures which are versatile intermediates in complex natural product synthesis. An application of the sequence to the synthesis of (+)-mesembrine illustrates the utility of these intermediates.
authors.affiliation: Department of Chemistry, Bryn Mawr College, Bryn Mawr, PA 19010-2899, USA.
authors.forename: Tapas
authors.initials: T
authors.lastname: Paul
authors.forename: William P
authors.initials: WP
authors.lastname: Malachowski
authors.forename: Jisun
authors.initials: J
authors.lastname: Lee