Highly Enantioselective Sequential Hydrogenation of Ethyl 2-Oxo-4-arylbut-3-enoate to Ethyl 2-Hydroxy-4-arylbutyrate

Abstract

The hydrogenation of (E)-ethyl 2-oxo-4-arylbut-3-enoate with [NH2Me2]+[{RuCl [(S)-SunPhos]}2(μ-Cl3)] gave ethyl 2-hydroxy-4-arylbutyrate with 94−96% ee. Further investigation has proved that the hydrogenation proceeded via a sequential hydrogenation of CO and CC bonds, which is sensitive to the reaction temperature. Hydrolysis of ethyl 2-hydroxy-4-phenylbutyrate (ee 93%) provided the 2-hydroxy-4-phenylbutyric acid with 81% yield at 99% ee after a single recrystallization from 1, 2-dichloroethylene