Synthesis of γ-and δ-Lactones by Free-Radical Annelation of Se-Phenyl Selenocarbonates
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.
Bachi, Mario D., and Eric Bosch. "Synthesis of. gamma.-and. delta.-lactones by free-radical annelation of Se-phenyl selenocarbonates." The Journal of Organic Chemistry 57, no. 17 (1992): 4696-4705.
Journal of Organic Chemistry