Synthesis of enantiomerically pure 2,2,3,4,5-pentasubstituted pyrrolidines by phenylsulfanyl migration.
[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.
Baldwin
I Craig
IC
OSI Pharmaceuticals, Watlington Road, Cowley, Oxford, OX4 5LY, England.
Briner
Paul
P
Eastgate
Martin D
MD
Fox
David J
DJ
Warren
Stuart
S