Nanocrystalline magnesium oxide stabilized gold nanoparticles: an advanced nanotechnology based recyclable heterogeneous catalyst platform for the one-pot synthesis of propargylamines

A simple and elegant synthesis of gold nanoparticles via counter ion stabilization of AuCl4- on nanocrystalline magnesium oxide support followed by sodium borohydride reduction is described here. A thorough characterization of the resulting heterogeneous material revealed the presence of uniformly distributed gold nanoparticles (10-12 nm) deposited on to (111) plane of quasi-crystalline icosahedral lattice of nanocrystalline magnesium oxide which exhibits excellent catalytic activity for the one pot synthesis of structurally divergent propargylamines via a three component coupling of an alkyne, an amine and an aldehyde without requiring any additives or inert atmosphere. The catalyst contains ultra low loading of gold (0.236 mol%), and turnover numbers as high as 400 are obtained. The catalyst can be isolated by simple centrifugation and reused for four cycles.