Chapter 6: Transfer Hydrogenation with Non-toxic Metals for Drug Synthesis

This chapter describes the application of metal-catalysed asymmetric transfer hydrogenation and borrowing hydrogen processes to the synthesis of pharmaceuticals. Special emphasis is given to recent developments using Earth-abundant catalysts for the development of more sustainable processes. Asymmetric transfer hydrogenation reactions provide an alternative to direct hydrogenation for the enantioselective synthesis of alcohols and imines. A hydrogen donor, in general an alcohol or formic acid, can be used as a source of hydrogen. In addition, borrowing hydrogen processes for the formation of C-N and C-C bonds is discussed. Creation of C-N and C-C bonds are important categories of reactions used in industrial medicinal chemistry. The development of simple and safe synthetic strategies with high atom economy and efficiency will provide invaluable input for discovery of new medicines.