High-Performance Ammonium Hypoiodite/Oxone Catalysis for Enantioselective Oxidative Dearomatization of Arenols

A high-performance enantioselective quaternary ammonium hypoiodite catalysis was developed for the dearomatization of arenols using oxone as an environmentally benign oxidant. The oxidation of not only 1- and 2-naphthols but also phenols, which were hardly reactive using the previous hypoiodite catalysis, readily proceeded under mild conditions, and only inorganic wastes were generated from the oxidant used. Control experiments and Raman analysis revealed the in situ generation of I+ such as hypoiodous acid as an unstable active species and molecular iodine (I2) as a stable dormant species. Most of the advantages of the present I+/oxone catalysis, compared to previous I+/(H2O2 or ROOH) systems, may result from generation of the stable dormant state and the higher reactivity of catalysts under acidic conditions.