A new ferrocenyl bisphosphorus ligand for the asymmetric hydrogenation of α-methylene-γ-keto-carboxylic acids

Upon incorporation of a noncovalent ion pair interaction, a new chiral ferrocenyl bisphosphorus ligand t-Bu-Wudaphos was developed. t-Bu-Wudaphos can be easily synthesized with very high diastereoselectivity as a highly air stable solid. The new ligand exhibited excellent reactivities and enantioselectivities in the asymmetric hydrogenation of α-methylene-γ-keto-carboxylic acids via an ion pair noncovalent interaction (up to >99% conversion, >99% ee).