Insight into the Mechanism of Oxidative Kinetic Resolution of Racemic Secondary Alcohols by Using Manganese( III )(Salen) Complexes as Catalysts

The oxidative kinetic resolution of various racemic secondary alcohols with PhI(OAc)(2) catalyzed by chiral [Mn(III)(salen)] complexes in the presence of KBr was studied in a water/organic solvent mixture. The dramatic, synergetic effect of additives, organic solvent, and the substituents of chiral salen ligands on the enantioselectivities of the reactions is reported. Results from UV/Vis spectroscopy and ESI-MS studies provide evidence that these reactions are induced by the formation of a high-valent manganese intermediate.