Platinum-Catalyzed Selective Hydration of Hindered Nitriles and Nitriles with Acid- or Base-Sensitive Groups

摘要

Hindered tertiary nitriles can be hydrolyzed under neutral and mild conditions to the corresponding amides using platinum(II) catalysts with dimethylphosphine oxide or other secondary phosphine oxides (SPOs, phosphinous acids) as ligands. We have found that this procedure also works well for nitriles with acid- or base-sensitive groups, which is unprecedented in terms of yield and selectivity. The catalyst loading can be as low as 0.5 mol %. Amides are isolated as the only product in high yield, and no further hydrolysis to the corresponding acids takes place. Reactions are carried out at 80 °C but take place even at room temperature. When enantiopure secondary phosphine oxide ligands are used in the hydrolysis of racemic nitriles, no kinetic resolution is observed, presumably due to racemization of the ligand during the reaction.