Synthesis of γ- and δ-Lactones by Free-Radical Annelation of Se-Phenyl Selenocarbonates

Article abstract of DOI:10.1021/jo00043a030

A general method for the synthesis of γ- and δ-lactones through the intramolecular addition of alkoxycarbonyl radicals, formed by reaction of Se-phenylselenocarbonates with n-Bu3SnH, onto carbon-carbon multiple bonds is described.This free-radical cyclization is characterized by high regioselectivity favoring exo addition and by a high ratio of cyclization to reduction.Monocyclic, fused bicyclic, and spirocyclic lactones are formed in good to excellent yield.Use of allyltri-n-butyltin as a chain-transfer agent in the place of n-Bu3SnH affords the corresponding 3-butenyl lactones.