Oxotitanium complexes useful as asymmetric reaction catalysts particularly for producing beta-hydroxy ketones or alpha-hydroxy carboxylic acid esters

摘要

A novel oxotitanium complex represented by general formula (I) is disclosed :wherein R¹ and R² may be hydrogen, lower alkyl, lower alkoxy, halogen, phenyl, substituted phenyl, trialkylsilyl, monoalkyldiphenylsilyl, dialkylmonophenylsilyl, triphenylsilyl, substituted triphenylsilyl, or lower alkoxycarbonyl ; R¹ and R² may be bonded to form a hydrocarbon ring with the ring carbon atoms ; R³ and R⁴ may be different and each represents hydrogen, lower alkyl, lower alkoxy, benzoyl, benzenesulfonyl, or halogen ; R³ and R⁴ may be bonded to form a hydrocarbon ring with the ring carbon atoms ; and n is 1 or 2. The novel oxotitanium complex is particularly useful as an asymmetric reaction catalyst in glyoxylate-ene or aldol reactions, and processes for producing β-hydroxy ketones or a-hydroxy carboxylic acid esters in its presence are also disclosed.