Date of Original Version
The vanadium-catalyzed oxidative coupling of substituted 2-arylimidiazo[1,2-a]pyridines to N-methylmorpholine oxide, which acts as both a coupling partner and an oxidant, has been achieved. This reaction was applied to various substituted imidiazo[1,2-a]pyridine and indole substrates, resulting in yields as high as 90%. Mechanistic investigations indicate that the reaction may proceed via a Mannich-type process. This work demonstrates how oxidative aminomethylation can be used as a useful method to introduce tertiary amines into heterocycles, thus providing an alternative method for conventional Mannich-type reactions.
Kaswan, P., Porter, A., Pericherla, K., Simone, M., Peters, S., Kumar, A., & DeBoef, B. (2015). Oxidative Cross-Coupling of sp3- and sp2-Hybridized C-H Bonds: Vanadium-Catalyzed Aminomethylation of Imidazo[1,2-a]pyridines. Organic Letters, 17(21), 5208-5211.
Available at: http://dx.doi.org/10.1021/acs.orglett.5b02539