THE FIRST EXAMPLE OF ASYMMETRIC MICHAEL REACTION CATALYZED BY CHIRAL ALKALI-METAL ALKOXIDES

Some chiral sodium alkoxides can be used as catalysts in the asymmetri c Michael reaction as exemplified by the 1,4-addition of an achiral Ni -II complex of the Schiff base derived from glycine and N-(2-pyridylca rbonyl)-o-aminobenzophenone (1) to methyl methacrylate (2) or methyl a crylate (14). The products of the reaction of 1 with 2, viz., the corr esponding diastereomeric complexes of 4-methylglutamic acid, are forme d in dissimilar amounts (de 26-85%); the ee value for the major diaste reomer (2S,4R)-3a is 28%. After recrystallization, the enantiomeric pu rity of complex 3a increases to ee > 85%. Acid-catalyzed hydrolysis of the enantiomerically enriched complex 3a affords (2S,4R)-4-methylglut amic acid tee > 85%). The complex of glutamic acid 15 resulting from t he reaction of 1 with 14 is formed with an ee of 45%. After recrystall ization, the enantiomeric purities of complex 15 and glutamic acid inc rease to ee > 90%.