Optimizing ligand structure for low-loading and fast catalysis for alkynyl-alcohol and -amine cyclization.

A series of [Ru(Cp/Cp*)(PN)(MeCN)]PF complexes were prepared, in which the steric and electronic properties of the primary coordination sphere were varied (R = Ph, t-Bu, Bn; and Cp vs. Cp*). These complexes were catalytically active in the cyclization of alkyne substrates with an intramolecular nucleophile (amine or alcohol) to produce 5- and 6-membered heterocycles.