Carbon-Nitrogen Bond Formation Involving Weil-Defined Aryl-Copper(lll) Complexes

摘要

Copper-mediated carbon-carbon and carbon-heteroatom coupling reactions have been known for more than 100 years; however, these reactions have been overshadowed by the scope and versatility of analogous Pd-catalyzed coupling methods. The dramatic success of Pd catalysis can be attributed, in part, to the availability of sophisticated insights into the fundamental organometallic chemistry of palladium, including knowledge of the reactivity of organopalladium complexes in oxidation states ranging from Pd~0 to Pd~(IV). Fundamental studies of organocopper chemistry could play a similar role in Cu catalysis, yet the organometallic chemistry of copper in oxidation states higher than +1 is almost completely unexplored. Only a small number of structurally characterized organo-coppen(III) complexes are known (Chart 1), and no studies of their reactivity toward C-C or C-X bond formation have been reported. Here, we present the first reactions of this type and provide preliminary mechanistic insights into C-N bond-forming reactions that arise from the reaction of arylcopper(III) complexes with neutral carboxamides and related nucleophiles. These observations complement recent in situ spectroscopic studies that provide evidence for alkylcoppen(III) intermediates in reactions of organocuprates, and they provide an important starting point for characterization of the fundamental organometallic chemistry of coppen(III).