Atom transfer radical cyclization of O-allyl-2,2-dichlorohemiacetal acetates: an expedient method to dichloro-γ-lactones

Abstract

3-Alkyl-3-chloro-4-chloromethyl-γ-lactones were synthesized in acceptable yields, exploiting the CuCl- N, N, N′, N″, N″-pentamethyldiethylenetriamine catalyzed atom transfer radical cyclization (ATRC) of O-allyl-2,2-dichlorohemiacetal acetates, starting materials easily prepared from 2,2-dichloroaldehydes. The oxidation of the intermediate dichloro-2-acetoxytetrahydrofurans was completed in a two-step, one-pot procedure: hydrolysis to γ-lactol and final oxidation to lactone with Jones' reagent.