Oxidative Cross-Coupling of sp³- and sp²-Hybridized C-H Bonds: Vanadium-Catalyzed Aminomethylation of Imidazo[1,2-a]pyridines

Pinku Kaswan, Birla Institute of Technology and Science, Pilani
Ashley Porter, University of Rhode Island
Kasiviswanadharaju Pericherla, Birla Institute of Technology and Science, Pilani
Marissa Simone, University of Rhode Island
Sean Peters, University of Rhode Island
Anil Kumar, Birla Institute of Technology and Science, Pilani
Brenton Deboef, University of Rhode Island

Abstract

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.