A theoretical investigation of the enantioselective reduction of prochiral ketones promoted by chiral diamines

A chiral diamide [(2S)-5-oxo-2-(arylamino)carbonylpyrrolidine] has been experimentally employed as an effective chiral catalytic precursor in the borane-mediated asymmetric reduction of prochiral ketones to produce the corresponding secondary alcohols. The mechanism of the reduction has been investigated theoretically by density functional theory, and the results reveal that this reaction is accomplished via four steps. Fully geometry optimized reactants, products, transition states, and intermediates are obtained. The analysis of these results reveals one pathway that is more energetically favorable, and its associated geometries correlate well with the final products of the reaction. Further calculations show that the solvent effect of toluene has no influence on the enantioselectivity of this reduction.