RuCl₃/PPh₃:  An Efficient Combination for the Preparation of Chiral 1,3-anti-Diols through Catalytic Hydrogenation

An efficient economical alternative to the commonly used Evans' reagent for the diastereoselective reduction of β-hydroxy ketones is reported. Thus, ruthenium-mediated hydrogenation of enantioenriched β-hydroxy ketones using RuCl₃ associated to achiral monophosphines allowed the preparation of a series of 1,3-anti-diols in good yields and with a high level of diastereoselectivity. A short screening of ligands pointed out PPh₃ as the most effective phosphine, and PCy₃ afforded the 1,3-diols with an unexpected moderate syn selectivity.