Regio- and diastereoselective reduction of nonenolizable α-diketones to acyloins mediated by indium metal

[GRAPHICS] a-Diketones are efficiently reduced with indium metal in methanol-water in the presence of NH4Cl, LiCl, or NaCl to give regio- and diastereoselectively the corresponding acyloins in good to excellent yield. The cleavage of the acyloins under Pb(OAc)(4)/MeOH-PhH condition provides a convenient and regioselective access to highly functionalized cyclopentane carboxaldehydes, potential building blocks in organic syntheses.