Iodine(III)-Mediated Enantioselective Oxidative Contraction of Dihydropyranones.

The γ-butyrolactone motif is promising in pharmaceuticals and natural products with various biological activities. The oxidative contraction of dihydropyranones mediated by hypervalent iodine (HVI) reagents is an efficient approach of preparing this motif. We show that, using readily available chiral HVI reagents, numerous enantioenriched γ-butyrolactones are accessible. The method provides generally high enantioselectivities and modest to high yields. The resulting chiral iodoarene is easily recovered and reused for the reaction multiple times, without loss of yield or enantioselectivities.