Investigation of binap-based hydroxyphosphine arene–ruthenium(ii) complexes as catalysts for nitrile hydration

Abstract

The binap-based hydroxyphosphine-(η⁶-arene)–ruthenium(II) complexes [RuX{η⁶:κ¹(P)-PPh₂-binaphthyl}{PPh₂(OH)}][OTf] (X = OTf (4), Cl (5)) have been evaluated as potential catalysts for the selective hydration of nitriles to primary amides. The triflate derivative 4 proved to be the most active, being able to hydrate a large variety of aromatic, heteroaromatic, α,β-unsaturated and aliphatic nitriles in pure water at 100 °C. The utility of complex 4 to promote the catalytic rearrangement of aldoximes has also been demonstrated. In addition, insights about the role played by the hydroxyphosphine ligand PPh₂(OH) during the catalytic reactions are given.