In Water Markovnikov Hydration and One-Pot Reductive Hydroamination of Terminal Alkynes under Ruthenium Nanoparticle Catalysis

In the presence of Shvo's catalyst [2,3,4,5-tetraphenyl-1,3-cyclopentadien-1-ol, ruthenium(II) complex], a small quantity of aniline and TGPS-750-M surfactant, terminal alkynes were hydrated under microwave (MW) dielectric heating in water as solvent with high conversion and good yield. The reaction gives the Markovnikov product exclusively, unlike that commonly observed with ruthenium complexes. Under the influence of MWs, Ru nanoparticles embedded in the nanomicelle environment were formed, acting as the effective hydration catalyst. Introducing sodium formate in the aqueous phase and using a stoichiometric amount of amines, the Ru nanoparticle nanomicelle catalyst gave the first example of one-pot single-step hydroamination of alkynes with the formation of the corresponding secondary amines. The reaction is characterized by low environmental impact as TGPS-750-M is required in low amount, and organic solvents employed only for product separation or catalyst recycling.