Recent advances of Cp*Ir complexes for transfer hydrogenation: focus on formic acid/formate as hydrogen donors.

Transfer hydrogenation reactions offer synthetically powerful strategies to deliver various hydrogenated compounds with the advantages of efficiency, atom economy, and practicability. On one hand, formic acid/formate function as promising hydrogen sources owing to their readily obtainable, inexpensive, and easy to handle nature. On the other hand, CpIr complexes show high activities in transfer hydrogenation. This review highlights progress achieved for transfer hydrogenation of CO, CC, and CN bonds of a variety of unsaturated substrates, as well as amides focusing on CpIr complexes as catalysts and formic acid/formate as hydrogen sources.