Reductive Cross-Coupling between Unactivated C(aryl)–N and C(aryl)–O Bonds by Chromium Catalysis Using a Bipyridyl Ligand

Reductive cross-coupling between two chemically inert bonds remains a great challenge in synthetic chemistry. We report here the reductive cross-coupling between unactivated C(aryl)–N and C(aryl)–O bonds that was achieved by chromium catalysis. The simple and inexpensive CrCl 2 salt, combined with important bipyridyl ligand and magnesium reductant, shows high reactivity in the successive cleavage of C(aryl)–N bonds of aniline derivatives and C(aryl)–O bonds of aryl esters, allowing the cross-coupling of these two unactivated and different bonds to occur in a reductive fashion to form a C(aryl)–C(aryl) bond. Mechanistic studies by deuterium-labeling experiments indicate that the C(aryl)–N bonds in anilines are preferentially cleaved by reactive Cr species, in which the ligation of bipyridyl with Cr by adopting a coordination model in 1:1 ratio can be considered.