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Mechanism of the enantioselective oxidation of racemic secondary alcohols catalyzed by chiral Mn(III)-salen complexes.

ABSTRACT: The experiments described here clarify the mechanism and origin of the enantioselectivity of the oxidation of racemic secondary alcohols catalyzed by chiral Mn(III)-salen complexes using HOBr, Br(2)/H(2)O/KOAc or PhI(OAc)(2)/H(2)O/KBr as a stoichiometric oxidant. Key points of the proposed pathway include (1) the formation of a Mn(V)-salen dibromide, (2) its subsequent reaction with the alcohol to give an alkoxy-Mn(V) species, and (3) carbonyl-forming elimination to produce the ketone via a highly organized transition state with intramolecular transfer of hydrogen from carbon to an oxygen of the salen ligand.

SUBMITTER: Brown MK

PROVIDER: S-EPMC2945693 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Mechanism of the enantioselective oxidation of racemic secondary alcohols catalyzed by chiral Mn(III)-salen complexes.

Brown M Kevin MK Blewett Megan M MM Colombe James R JR Corey E J EJ

Journal of the American Chemical Society 20100801 32

The experiments described here clarify the mechanism and origin of the enantioselectivity of the oxidation of racemic secondary alcohols catalyzed by chiral Mn(III)-salen complexes using HOBr, Br(2)/H(2)O/KOAc or PhI(OAc)(2)/H(2)O/KBr as a stoichiometric oxidant. Key points of the proposed pathway include (1) the formation of a Mn(V)-salen dibromide, (2) its subsequent reaction with the alcohol to give an alkoxy-Mn(V) species, and (3) carbonyl-forming elimination to produce the ketone via a high ...[more]

PMID: 20666410

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