A New Access to Enantiopure syn‐ and anti‐2‐Methyl‐1,3‐diol Moieties from Chiral Nonracemic α‐Bromo α′‐Sulfinyl Ketones Promoted by Samarium Diiodide

Abstract syn‐ and anti ‐2‐Methyl‐1,3‐diols have been prepared by a two‐step sequence that involves a SmI 2 ‐promoted stereoselective Reformatsky addition of chiral nonracemic α‐bromo α′‐sulfinyl ketones to various aldehydes followed by stereoselective reduction of the Reformatsky adduct. The absolute configuration of the products was determined by comparison with literature data and by 1 H NMR NOESY experiments. The observed stereoselectivities can be explained in terms of a boat transition state. Functionalization of the aldehyde and removal or transformation of the chiral sulfoxide will allow this methodology to be applied to the total synthesis of biologically active molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)