Cooperative catalysis of samarium diiodide and mercaptan in a stereoselective one-pot transformation of 5-oxopentanals into delta-lactones

[GRAPHICS] We demonstrate a general method for conversion of various 5-oxopentanals to substituted delta-lactones and 1-oxa-2-decalones by the synergistic cataly sis of samarium diiodide and 2-propanethiol (or disulfide), The deliberate use of mercaptan is advantageous to facilitate the catalytic cycle, This me thod shows high stereoselectivities, and an enantioselective procedure is f easible by using the chiral mercaptan (1R,2S)-1 phenyl-2-(N-acetamido)propa nethiol as a promoter.