Preparation of [alpha]-keto acids and [alpha]-keto esters using transition metal carboxylate complexes

Abstract

Screening for nickel (II) carboxylate complexes disclosed that nickel (II) stearate coupled with THBP could catalyze the transformation of ethyl phenylacetate to ethyl benzoylformate as a major product and ethyl mandelate as a minor product. In the case of iron (III) carboxylate complexes, iron(III) trichloroacetate coupled with THBP could smoothly catalyze the transformation of ethyl phenylacetate to ethyl benzoylformate in high yield. The optimum conditions for the oxidation of ethyl phenylacetate including amount and type of catalyst, amount and type of oxidant, solvent, reaction time and reaction temperature were conducted. Utilizing the developed optimum conditions for the oxidation of ethyl phenylacetate, other selected chemical models: ethyl mandelate, ethyl thiophene-2-acetate, ethyl (4-chlorophenyl) acetate, methyl (4-methoxyphenyl) acetate, ethyl (4-methoxyphenyl) acetate, butyl (4-methoxyphenyl) acetate and ethyl p-toluylacetate could be converted to corresponding [alpha]-keto esters in good to excellent yield.