Stereochemical studies on radical cyclization of N-Aziridinyl imines

Abstract

The radical cyclizations using N-aziridinylimines for the formation of five- and six-membered ring radicals from acyclic precursors are different from ordinary radical cyclizations using alkenyl groups as acceptors In particular, stereochemical outcome of these two cyclizations should be quite different. The competition reaction between exo- and endo-cyclization of alkene and imino group as a radical acceptor was investigated and this result indicated the radical cyclization of alkyl radical to alkene yielded cis- cyclized product as major product but imino group yielded trans-product. The radical cyclization of xanthate in presence of N-aziridinylimine provided same amount of cis- and trans-product, contrast to the Beckwith``s result. Furthermore, the competition reaction between keto and imino group showed different stereochemical products. The radical cyclization of various radical precursors to imino group afforded trans-cyclized products as major product.