Samarium diiodide-mediated asymmetric reactions of 8-phenylmenthyl esters

(−)-8-Phenylmenthol was used as a chiral auxiliary to direct asymmetric reactions of its preformed carboxylates. Reduction of xanthates 1a and 1b by SmI2 likely proceeded via HMPA-bound samarium enolate intermediates. Self- and cross-pinacolic coupling reactions of 8-phenylmenthyl α-oxoesters were achieved in a highly stereoselective manner by treatment with SmI2 at −78°C. The stereochemical outcome was consistent with a chelated mode of transition states.