title: Synthesis of enantiomerically pure 2,2,3,4,5-pentasubstituted pyrrolidines by phenylsulfanyl migration.
abstract: [reaction: see text] Enantiomerically pure 2,2,3,4,5-pentasubstituted pyrrolidines can be prepared, in high overall yield, from alpha,beta-unsaturated esters. Asymmetry is introduced via a Michael addition, and additional stereogenic centers are introduced by an aldol reaction. A novel stereospecific ring-forming reaction, proceeding via a thiiranium (episulfonium) ion, yields pyrrolidines from beta-hydroxy sulfides. In this manner, 2,2,3,4,5-pentasubstituted pyrrolidines, containing three contiguous stereogenic centers around the ring, can be prepared in 44% overall yield from ethyl crotonate.
authors.affiliation: OSI Pharmaceuticals, Watlington Road, Cowley, Oxford, OX4 5LY, England.
authors.forename: I Craig
authors.initials: IC
authors.lastname: Baldwin
authors.forename: Paul
authors.initials: P
authors.lastname: Briner
authors.forename: Martin D
authors.initials: MD
authors.lastname: Eastgate
authors.forename: David J
authors.initials: DJ
authors.lastname: Fox
authors.forename: Stuart
authors.initials: S
authors.lastname: Warren