Gold Catalysts for Selective Hydrogenations: The Role of Heterolytic H2 Dissociation

Hydrogenations are fundamental transformations in organic synthesis, and the industrial applications span from food, petrochemical, fine chemicals to pharmaceuticals synthesis where hydrogenations of multifunctional molecules should be carried out in a chemoselective way. In this concept article we aim at providing an overview on the activation of molecular hydrogen (H2) via heterolytic dissociation, which is responsible to unlock high activity of gold catalysts for chemoselective hydrogenations. The key benefit of heterolytically dissociated H species is their preference for hydrogenating polar unsaturated groups like C=O, C=N, and C=S, as these polar bonds are ideal acceptors for proton and hydride pairs. We will provide examples on how to obtain enhanced chemoselectivity on alkynes, a, b-unsaturated aldehydes and nitro-compounds hydrogenations with gold catalysts.