The 5- exo- trig radical cyclization reaction under reductive and oxidative conditions in the synthesis of optically pure GABA derivatives

Abstract

Free radical precursors 4a and 4b were synthesized and treated under reductive or oxidative conditions to obtain the corresponding optically pure pyrrolidinones 5– 8 , which were subsequently transformed into corresponding optically pure GABA derivatives 9– 11 . When reductive radical conditions ( 4a → 7 and 8 ) were used, a Ph 1–5 migration product 14 was obtained; presumably depending upon the specific conformation of the rotamer precursor and also 14 was found to be a kinetic product.