Micro-structured reactors as a tool for chiral modifier screening in gas–liquid–solid asymmetric hydrogenations

A continuous micro-structured reactor equipped with a perforated (5 μm) membrane is used for the investigation of the gas–liquid–solid asymmetric hydrogenation of ethylpyruvate on a Pt/γ-Al 2O 3 catalyst modified with chiral inductors under high hydrogen pressure (45 bar). Up to eight chiral inductors have been evaluated, the best enantioselectivity (63%) being obtained with cinchonidine. The very low reaction volume (100 μl) offers short operating time. Solvent effect, deactivation studies and the effect of modifier leaching are also reported.