Carbene reactions of alpha-oxacyclo- and alpha-azacyclo-N-aziridinylimines: Effect of heteroatom and ring size in the ring expansion reaction

Abstract

Carbenes, generated from thermolysis of alpha-oxacyclo- and alpha-azacyclo-N-aziridinylimines in refluxing toluene, underwent ring expansions via insertion of alkyl carbenes into carbon-carbon bonds and intramolecular ammonium ylide formations, respectively. Ring expansion reaction of alpha-oxetanyl-N-aziridinylimines occurred via alkylidenecarbene intermediates, whereas thermal reaction of alpha-azetidinyl-N-aziridinylimines afforded alpha-aminoacetylene compounds via 1,2-H migration of alkylidenecarbene intermediates.