New catalysts for the asymmetric hydrosilylation of ketones discovered by mass spectrometry screening.

A method for determining enantiomeric excess by mass spectrometry was employed to screen a family of chiral phosphite P,N-ligands for activity in the rhodium-catalyzed asymmetric hydrosilylation of ketones. The identification of an effective set of ligands was followed by preliminary studies of the reaction scope and mechanism. Asymmetric induction of 84-88% ee for larger-scale reactions was observed, which is close to the level of the best alternative catalysts previously discovered. The screening method was shown to be applicable to a variety of substrates without the need for special optimization.