Highly diastereo- and enantioselective organocatalytic addition of acetone to beta-substituted alpha-ketoesters via dynamic kinetic resolution

L-Proline catalyzes the aldol addition reaction of acetone to beta-substituted alpha-ketoesters with dynamic kinetic resolution, providing the desired adduct in good yield with excellent diastereoselectivity ( up to >99:1 dr) and enantioselectivity (up to 98% ee). The absolute configuration of the chiral adduct was assigned by single-crystal X-ray diffraction analysis. A tentative explanation of the stereochemical outcome is proposed.