ENZYME-CATALYZED ADDITION OF HYDROCYANIC ACID TO SUBSTITUTED PIVALALDEHYDES - A NOVEL SYNTHESIS OF (R)-PANTOLACTONE

(R)-Cyanohydrins (R)2b-h are obtained in good optical yields by (R)-ox ynitrilase catalyzed enantioselective addition of HCN to beta-substitu ted pivalaldehydes 1b-h. Under optimized reaction conditions with high ly purified (R)-oxynitrilase, hydroxypivalaldehyde (1a) is converted t o (R)-2a in satisfactory chemical and optical yields. By acid-catalyze d hydrolysis the cyanohydrins (R)-2a-h cyclize directly to give crude (R)-pantolactone (R)-3 with ee-values of 56-95% which, after recrystal lization, go up to greater than or equal to 98%ee in all cases.