Supported gold nanoparticles catalyzed cis-selective semihydrogenation of alkynes using ammonium formate as the reductant

TiO2 supported gold nanoparticles with low loading (0.5 mol%) are able to semihydrogenate non -fluorinated and gem-difluorinated alkynes to cis-alkenes with high selectivity, using cost-effective and easy-to-handle ammonium formate as the reductant. No over-reduction was observed. The good recyclability of Au/TiO2 allows for green semireduction of alkynes. A difluorinated pyran and ce,p-unsaturated 8-lactone were easily prepared from the obtained gem-difluoro alkene building blocks.