A Bifunctional Aminoxyl–Bipyridine Peptide Catalyst for the Atroposelective Copper-Catalyzed Aerobic Oxidation of Biaryl Diols

This catalyst was found to efficiently catalyze atroposelective oxidations using ambient air as the terminal oxidant. Additionally, catalyst bifunctionality was found to be essential for enantioselectivity in this desymmetrization, affording axially chiral products in up to >99.5:0.5 <i>er</i>, facilitated by combined initial enantiotopic group selection followed by varying levels of secondary kinetic resolution. Central to catalyst design is the synthesis and incorporation of bipyridylalanine into an aminoxyl-containing peptide.

Mechanistic studies reveal a first-order kinetic profile on the catalyst, which, in combination with computational experiments, suggest that the aminoxyl and bipyridyl moieties of a single bifunctional peptide function in unison throughout the catalytic cycle.