Enantioselective reduction of ketones with a silane agent/metal compound/ chiral ligand system

Abstract

A process for the enantioselective reduction of prochiral ketones to chiral alcohols by (a) the reaction of a prochiral ketone with a silane agent, which is present in a stoichiometric quantity, in the presence of a catalyst derived from a Zn, Co or Cd precursor compound and from a chiral amine, imine, alcohol or amino alcohol ligand; (b) the hydrolysis of the siloxane obtained using an appropriate agent; and (c) the separation and purification of the optically active alcohol formed. Polymethylhydrosiloxane (PMHS) is a preferred silane agent, zinc is a preferred metal, and the precursor compound is produced by reacting a salt or complex of the respective metal with the reducing agent. In another embodiment, an appropriate salt of the chosen metal is used directly in the reaction with the chiral ligand to produce the catalytic form after reaction with the ligand. The process enables high enantiomeric excesses (ee) to be obtained in chiral alcohols.

Dependencies are inferred from the claim text.