Free-Radical Chemistry of Imines

Abstract

Aryl radicals bearing an aldimino functional group as part of an ortho substituent cyclized by addition to C and/or N of the imino group. When the choice was between 5-exo closure to C and 6-endo closure to N, the former predominated. However, 6-endo closure to C predominated over 5-exo cyclization to N in isomeric imines. Absolute values of cyclization rate constants were determined and an explanation for the unusual 6-endo preference is offered. Chiral induction in 6-endo cyclization to C of an aldimine from D-glyceraldehyde acetonide was observed, and its sense was determined.