Hydrogenation of Carboxylic Acids Catalyzed by Half-Sandwich Complexes of Iridium and Rhodium

by Timothy P. Brewster, Alexander J. M. Miller *, D. Michael Heinekey , Karen I. Goldberg*

A series of half-sandwich Ir and Rh compounds are demonstrated to be competent catalysts for the hydrogenation of carboxylic acids under relatively mild conditions. Of the structurally diverse group of catalysts tested for activity, a Cp*Ir complex supported by an electron-releasing 2,2′-bipyridine ligand was the most active. Higher activity was achieved with employment of Brønsted or Lewis acid promoters. Mechanistic studies suggest a possible reaction pathway involving activated carboxylic acid substrates. The hydrogenation reaction was shown to be general to a variety of aliphatic acids.

Journal of the American Chemical Society

Article first published online: 21 OCT 2013

DOI: 10.1021/ja408149n