Substituent Effect on Catalytic Activities of [{η5‐Ar4C4COC(O)Ar}Ru(CO)2Cl] in Racemization and DKR of Secondary Alcohols

The derivatives of [{η5‐Ph4C4COC(O)Ph}Ru(CO)2Cl] were synthesized to investigate the substituent effect of the ruthenium complexes on the racemization and the chemoenzymatic dynamic kinetic resolution (DKR) of secondary alcohols, in which the phenyl rings are substituted with several different groups. Derivatives with electron‐donating substituents showed better activities than those with electron‐deficient ones, both in the racemization and in the DKR. The ruthenium complex, [{η5‐Ar4C4COC(O)Ar}Ru(CO)2Cl] (Ar=4‐methoxyphenyl), showed an activity about 14 times higher than that of [{η5‐Ph4C4COC(O)Ph}Ru(CO)2Cl] in the racemization of 1‐phenylethanol.