t-Butyl (R)-(-)-4-Cyano-3-hydroxybutyrate and process for its preparation.

摘要

t-Butyl (R)-(-)-4-cyano-3-hydroxybutyrate is disclosed having an optical purity of 99%ee or higher. A process for producing it consists of cyanogenation of a t-butyl (S)-(-)-4-halogeno-3-hydroxybutyrate (obtained by enantioselective hydrogenation of a t-butyl 4-chloro- or bromo-acetoacetate) in an aprotic polar solvent, by adding an aqueous solution of sodium or potassium cyanide and stirring at 15-100 DEG C for 2 to 5 hours. Recrystallization of the resulting crude product gives the optically active compound with high optical purity. The product can be used as an intermediate for making medicines.