The approaches through introduction of a keto group to a carbonyl group have also been applied to the synthesis of α-keto acid derivatives. For example, Wasserman et al. developed a method through the formation and singlet oxygen oxidation of enamino carbonyl intermediates. 6 On the other hand, direct oxidation of aryl acetic esters with hydrogen peroxide or molecular oxygen in the presence of transition metal catalyst has recently been reported. 7 Since aryl acetic ...
