Ru-Catalyzed Enantioselective Hydrogenation of Diaryl 1,4-Diketones: Synthesis of Chiral 1,4-Diarylbutane-1,4-Diols.

Asymmetric hydrogenation of diaryl 1,4-diketones was achieved by using trans -RuCl 2 [( S )-BINAP)][( S )-Daipen] as the catalyst and the reaction gave rise to excellent enantio- and diastereoselectivities (up to >99% ee and de ). This procedure provides a convenient and efficient synthetic method for chiral 1,4-diarylbutane-1,4-diols, which are important intermediates for a variety of chiral auxiliaries and ligands.