Hydrogenation of C-C multiple bonds mediated by [Pd(NHC)(PCy3)] (NHC=N-heterocyclic carbene) under mild reaction conditions

Pd(SIPr)(PCy₃)] (1; SIPr=N,N-(bis(2,6-diisopropylphenyl)imidazolidine), which is stable under H₂, was shown to be a highly active catalyst for the hydrogenation of a wide range of alkenes and alkynes. Reactions proceed under mild conditions (relatively low Pd loading, RT, low pressures of H₂) even when sterically hindered alkenes (tri- and tetra-substituted) are used.