Copper-mediated Regioselective C–H Cyanation of Phenols with Assistance of Bipyridine-type Bidentate Auxiliary

A Cu-mediated ortho-selective C–H cyanation of phenols with ethyl cyanoformate as the cyano source has been developed. The key to success is the introduction of 4,4′-di-tert-butyl-2,2′-bipyridine (dtbpy) bidentate auxiliary on the phenol oxygen, which is easily attachable, detachable, and recyclable. The newly developed protocol is tolerant of several carbonyl functional groups, which are incompatible with previous Lewis-acid-promoted cyanation of phenols. A Cu-mediated ortho-selective C–H cyanation of phenols with ethyl cyanoformate as the cyano source has been developed. The key to success is the introduction of 4,4′-di-tert-butyl-2,2′-bipyridine (dtbpy) bidentate auxiliary on the phenol oxygen, which is easily attachable, detachable, and recyclable. The newly developed protocol is tolerant of several carbonyl functional groups, which are incompatible with previous Lewis-acid-promoted cyanation of phenols.