Multifaceted catalytic hydrogenation of amides via diverse activation of a sterically confined bipyridine–ruthenium framework

Amides are ubiquitous and abundant in nature and our society, but are very stable and reluctant to salt-free, catalytic chemical transformations. Through the activation of a “sterically confined bipyridine–ruthenium (Ru) framework (molecularly well-designed site to confine adsorbed H(2) in)” of a precatalyst, catalytic hydrogenation of formamides through polyamide is achieved under a wide range of reaction conditions. Both C=O bond and C–N bond cleavage of a lactam became also possible using a single precatalyst. That is, catalyst diversity is induced by activation and stepwise multiple hydrogenation of a single precatalyst when the conditions are varied. The versatile catalysts have different structures and different resting states for multifaceted amide hydrogenation, but the common structure produced upon reaction with H(2), which catalyzes hydrogenation, seems to be “H–Ru–N–H.”