Chiral Phosphites Derived from Carboranes: Electronic Effect in Catalytic Asymmetric Hydrogenation

A series of new fine-tunable monodentate phosphite and phosphoramidite ligands based on carboranes have been synthesized and used for asymmetric Rh-catalyzed hydrogenation of prochiral olefins with the result of up to 99.8% ee. Dependence of the enantio selectivity on the electron-withdrawing or electron-donating properties of the carboranyl substituent has been studied. Chirality 21:2-5, 2009. (C) 2008 Wiley-Liss, Inc.