Lipase-catalyzed dynamic kinetic resolution giving optically active cyanohydrins: use of silica-supported ammonium hydroxide and porous ceramic-immobilized lipase

Synthetically useful cyanohydrin acetates, ArCH(OAc)CN (Ar=C₆H₅, 3,4-methylenedioxyphenyl, 4-Me-C₆H₄, 4-Cl-C₆H₄, 4-F-C₆H₄, 4-CF₃-C₆H₄), were successfully synthesized in high enantiomeric purities (79-93% ee) via the lipase-catalyzed dynamic kinetic resolution (DKR) of cyanohydrins synthesized in situ from the corresponding aldehydes and acetone cyanohydrin. The combined use of silica-supported BTAH (benzyltrimethylammonium hydroxide) and porous ceramic-immobilized lipase under the optimized reaction conditions enabled the remarkable acceleration of the enantioselective DKR reactions.