Density functional (BHandH) calculations, using 6-31G** basis set, have been employed to study the reaction mechanism of the enantioselectivity in a chiral 1,3,2-oxazaphospholidine-borane catalyzed reduction of acetophenone. Our calculations confirm that title reaction consists of two parallel step processes, in which complexes, TS, intermediates and enantiomer middle products are located on the enantioselective reaction pathway between oxazaphospholidine borane adduct and acetophenone. In the re-duction products of acetophenone are mainly in (R) configuration. In addition, solvent effects of reaction were studied with the PCM model. It was found that the mechanism did not change as the toluene solvent was introduced, but the energies of stationary points and the barriers for the rate-controlling step in (R) reaction were lower than those in the gas phase. This indicates that the enantioselective reaction (R) can take place in solution more easily.

Key words: enantioselective, oxazaphospholidine, borane, acetophenone, mechanism