Method for preparing a biologically active 2-substituted succinic acid derivative involving asymmetrically catalytically hydrogenating the corresponding 2(E)-alkylidene succinate derivative in the presence of a rhodium complexed (R,R)-bisphosphine compound.

K. Achiwa, Tetrahedron Lett., 1475 (1978), discloses catalytic reduction of itaconic acid at pressures of 52.7 kg/cmhydrogen with a catalyst generated in situ from N-acyl-3,3 sec -bis(diphenylphos-phino) pyrrolidine and chloro rhodium octadiene dimer to produce the corresponding S-enantiomer succinic acid(cas:110-15-6) with optical purities ranging from 30-83%. Reduction of the sodium salt of itaconic acid with the same catalyst produced the S-enantiomer succinic acid with 92% ee. Ojima et al., Chem. Lett., 567 (1978) and Ojima et al., Chem. Lett. 1145 (1978).

Kawano et al., Tetrahedron Lett., 28, 1905 (1987) disclose reduction of itaconic acid with a ruthenium complex of optically active 2,2 min -bis(diphenylphosphino)-1,1 min -binaphthyl to produce the S-enantiomer succinic acid(cas:110-15-6) derivative with 88% optical purity. Kawano et al., also disclose reduction of the 1-mono ester and diester with 79 and 68% ee of the S-enantiomer respectively; and reduction of 2-phenylitaconic acid and 3-methoxyphenylitaconic acid to the corresponding S-enantiomer succinic acid derivatives with 90 and 84% ee respectively.

The present invention is directed to asymmetric homogeneous hydrogenation of certain 2(E)-alkylidene mono-substituted succinic acid derivatives to produce the corresponding (R)-succinic acid(cas:110-15-6) derivatives which are useful for synthesizing certain enzyme inhibitors.