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

3-Alkyl-3-chloro-4-chloromethyl-gamma-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 gamma-lactol and final oxidation to lactone with Jones' reagent. (C) 2009 Elsevier Ltd. All rights reserved.