Reductive Cross-Coupling between Unactivated C(aryl)-N and C(aryl)-O Bonds by Chromium Catalysis Using a Bipyridyl
Jinghua Tang1, Fei Fan1, Xuefeng Cong1
1Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China.
Abstract:
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 CrCl2 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.
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