The first example of asymmetric Michael reaction catalyzed by chiral alkali metal alkoxides

Some chiral sodium alkoxides can be used as catalysts in the asymmetric 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-pyridylcarbonyl)-o-aminobenzophenone (1) to methyl methacrylate (2) or methyl acrylate (14). The products of the reaction of 1 with 2, viz., the corresponding diastereomeric complexes of 4-methylglutamic acid, are formed in dissimilar amounts (de 26-85%); the ee value for the major diastereomer (2S,4R)-3a is 28%. After recrystallization, the enantiomeric purity of complex 3a increases to ee > 85%. Acid-catalyzed hydrolysis of the enantiomerically enriched complex 3a affords (2S,4R)-4-methylglutamic acid tee > 85%). The complex of glutamic acid 15 resulting from the reaction of 1 with 14 is formed with an ee of 45%. After recrystallization, the enantiomeric purities of complex 15 and glutamic acid increase to ee > 90%.