CHIRAL RUTHENIUM CATALYSTS FOR ASYMMETRIC HYDROGEN TRANSFER REDUCTION OF ACETOPHENONE - ORIGINAL EFFECT OF ASBESTOS ON ENANTIOSELECTIVITY

The preparation of new chiral ruthenium complexes of (+)-diphenyl-phosphinite-pantolactone and (+)-diop is reported. Their catalytic properties in asymmetric hydrogen transfer from 2-propanol to acetophenone are investigated. In the framework of this reaction, the ability of asbestos to influence the kinetics, yield and enantioselectivity of asymmetric catalysis is evidenced. Using the complex [Ru(OAc)2((+)-diop)]n the overall optical yield changes from 12% in (+)-alcohol in the absence of asbestos, to 19% in (-)-alcohol in the presence of asbestos. Kinetic studies emphasize the determining influence of the activation conditions, the one-electron ligand of the ruthenium complex, and the ratio g[asbestos]/mol [Ru]. © 1990.