High-speed and highly stereoselective hydrogenation of simple ketones

Hydrogenation of ketones is amongst one of the most important synthetic reactions. This transformation is not only of academic interest, but also of industrial significance because of its simplicity, environmentally friendliness, and economic viability. trans-RuCl2 (phosphine)(2)(1,2-diamine), when coupled with a strong base in 2-propanol, acts as the most reactive catalyst for homogeneous hydrogenation of ketones. This reaction, unlike conventional hydrogenation, proceeds selectively at a C=O bond leaving coexisting C=C linkages intact. Furthermore, rapid, highly productive asymmetric hydrogenation of simple ketones has been realized by using trans-RuCl2[(S)-tolbinap] [(S, S)-dpen] or its optical antipode. When acetophenone is hydrogenated with the complex, the turnover number reaches 2,400,000 and the turnover frequency as high as 228,000 h(-1) or 63 s(-1). When XylBINAP is used as a chiral phosphine, a wide variety of prochiral ketones are hydrogenated in up to 100% ee. This practical asymmetric hydrogenation will greatly facilitate the synthesis of biologically active compounds and functional materials.