A Combined Theoretical and Experimental Investigation on the Enantioselective Oxidation of Aryl Benzyl Sulfides in the Presence of a Chiral Titanium Catalyst

An experimental investigation of the enantioselective oxidation of aryl benzyl sulfides by tort-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.