Metalloenzyme-Inspired Catalysis: Selective Oxidation of Primary Alcohols with an Iridium-Aminyl-Radical Complex

摘要

Complexes of redox-active metals and oxygen-centered radicals (tyrosinyl (TyrO.), O·-, or O2·-) have highly specific functions in biological systems. The copper-dependent metalloenzyme galactose oxidase (GOase) specifically dehydrogenates (oxidizes) primary alcohols to the corresponding aldehydes at very high turn over frequencies (TOF) of greater than 2.5*106 h-1. The simplified catalytic cycle shown in Scheme 1 highlights the roles of the Cu2+ center and the coordinated TyrO. radical in this process. The catalytic cycle starts with the coordination of the alcohol substrate R-CH2OH to the Cu2+ center, in proximity to the TyrO. radical (Scheme 1 a).