Identification of the Side Products That Diminish the Yields of the Monoamidated Product in Metal-Catalyzed C–H Amidation of 2-Phenylpyridine with Arylisocyanates

The Ru(II)-catalyzed amidation of 2-arylpyridines with aryl isocyanates via C–H bond activation is less efficient than described previously, due to the formation of a series of side products, which were readily identified using direct infusion electrospray mass spectrometry and high-performance liquid chromatography–mass spectrometry.