Catalytic Hypervalent Iodine Oxidation Using 4-Iodophenoxyacetic Acid and Oxone®: Oxidation of p-Alkoxyphenols to p-Benzoquinones

A catalytic hypervalent iodine oxidation of p-alkoxyphenols using 4-iodophenoxyacetic acid (1a) and Oxone (R) was developed. Reaction of p-alkoxyphenol (2) with a catalytic amount of la in the presence of Oxone (R) as a co-oxidant in 2,2,2-trifluoroethanol-water (1 : 2) gave the corresponding p-qui none (3) in excellent yield without special operation. The substituent effect on iodobenzene ring in the oxidation was observed; p-alkoxy is the most effective, with the series following the approximate order p-RO>p-Me. o-MeO, m-MeO>H>o-CO2H. And remarkable solvent effects were observed.