Selective Hydrogenation of Benzophenones to Benzhydrols. Asymmetric Synthesis of Unsymmetrical Diarylmethanols

Abstract

[reaction: see text] trans-RuCl2[P(C6H4-4-CH3)3]2(NH2CH2CH2NH2) acts as a highly effective precatalyst for the hydrogenation of a variety of benzophenone derivatives to benzhydrols that proceeds smoothly at 8 atm and 23-35 degrees C in 2-propanol containing t-C4H9OK with a substrate/catalyst ratio of 2000-20000. Use of a BINAP/chiral diamine Ru complex effects asymmetric hydrogenation of various ortho-substituted benzophenones and benzoylferrocene to chiral diarylmethanols with consistently high ee.