Frustrated Lewis Pair Catalyzed Hydrogenation of Amides: Halides as Active Lewis Base in the Metal-Free Hydrogen Activation

A method
for the metal-free reduction of carboxylic amides using
oxalyl chloride as an activating agent and hydrogen as the final reductant
is introduced. The reaction proceeds via the hydrogen splitting by
B­(2,6-F2-C6H3)3 in combination
with chloride as the Lewis base. Density functional theory calculations
support the unprecedented role of halides as active Lewis base components
in the frustrated Lewis pair mediated hydrogen activation. The reaction
displays broad substrate scope for tertiary benzoic acid amides and
α-branched carboxamides.