A challenging direct asymmetric hydrogenation of (E)-2-oxo-4-arylbut-3-enoic acids to give 2- hydroxy-4-arylbutanoic acids (85.4− 91.8% ee) was achieved with a Ru catalyst based on SunPhos as the chiral ligand. Further investigation of the reaction revealed that partial isomerization of 2-hydroxy-4-arylbutenoic acids was involved in the hydrogenation process. Employing the reaction conditions to the hydrogenation of 2-oxo-4-phenylbutanoic acid ...
