Tandem enantioselective organo- and biocatalysis: a direct entry for the synthesis of enantiomerically pure aldols

Direct proline-catalyzed aldol reactions were linked in sequence with lipase-catalyzed kinetic resolutions to afford enantiomerically pure (>99% ee) aldol adducts in higher conversion than a standard resolution of racemic materials. The combination of organocatalytic aldol reactions and enzymatic kinetic resolutions provided exclusively either the (R)- or (S)-enantiomer of the aldol adducts even though an (R)-selective lipase catalyzed the kinetic resolutions. Furthermore, the one-pot tandem reactions are inexpensive, are operationally simple, circumvents the use of organic solvent and are environmentally benign.