A combined theoretical and experimental investigation on the enantioselective oxidation of aryl benzyl sulfides in the presence of a chiral titanium catalyst.

Francesco Naso, Maria Annunziata M Capozzi, Andrea Bottoni, Matteo Calvaresi, Valerio Bertolasi, Francesco Capitelli, Cosimo Cardellicchio

Index: Chemistry 15(48) , 13417-26, (2009)

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Abstract

An experimental investigation of the enantioselective oxidation of aryl benzyl sulfides by tert-butyl hydroperoxide in the presence of a titanium/hydrobenzoin catalyst has shown that these sulfides are ideal substrates for this catalytic system, with negligible interference by the substituents on the aryl groups. A reaction mechanism based on DFT computations has been proposed. The DFT MPWB1K functional was used in the theoretical investigation to account for weak hydrogen-bonding and pi interactions. The computed reaction profile explains the experimentally observed enantioselectivity, which is determined by the thermodynamics of the first phase of the reaction. A detailed discussion of the hydrogen-bonding and pi interactions that drive the reaction along the observed stereochemical path is given.