Bio-inspired copper catalyst can be used in conjunction with aerial dioxygen for benzylic oxidative coupling. 

Aerial dioxygen is the most environmentally-friendly and cheapest reactant for oxidising organic substrates. However, because of its kinetic inertness, dioxygen needs to be activated before it can be used in oxidation chemistry. To perform this task under mild conditions, nature has evolved clever enzymes that contain either iron or copper ions within their active sites. Some of the enzymes have two proximate metal ions which act in concert during the catalytic reaction. 

Inspired by nature, Franc Meyer and co-workers, at Georg-August-Universität, Göttingen, Germany, have developed a copper catalyst containing two copper ions in close proximity. These ions are reminiscent of some enzyme active sites. This dicopper complex acts as a catalyst in the selective oxidative coupling of certain phenols under aerobic oxidations and at room temperature. 'Products that result from the coupling of phenols may represent valuable compounds with potential industrial applications,' says Meyer. 

In order to gain a first insight into the reaction mechanism for the present system, Meyer managed to characterise a stable reaction intermediate using a series of spectroscopic analyses. 

A future challenge will be to provide a full picture of how the two proximate metals cooperate during catalysis. This would allow the application of this bio-inspired approach to a broad range of substrate transformations. 

Kathleen Too