ASYMMETRIC SYNTHESIS. PRACTICAL PRODUCTION OF D AND L THREONINE. DYNAMIC KINETIC RESOLUTION IN RHODIUM AND RUTHENIUM CATALYZED HYDROGENATION OF 2-ACYLAMINO-3-OXOBUTYRATES.

Article abstract of DOI:10.1016/S0957-4166(00)86108-X

Enantioselective syntheses of D and L threonine are described.Racemic methyl and ethyl 2-acylamino-3-oxobutyrate 1 were synthesized from the corresponding acetoacetates 6 and then hydrogenated stereoselectively via dynamic kinetic resolution with various chiral P ^* P Rh(I) 8 and Ru(II) 10 catalysts to give syn optically active alcohols which could be converted by hydrolysis and treatment with propylene oxide into threonine.The best results were obtained using (-) CHIRAPHOS Ru and (+) BINAP Ru as catalysts, in the hydrogenation step leading respectively to D threonine (ee : 99percent) and L threonine (ee : 94percent) in 26-34percent overall yields.