1564262-84-5Relevant academic research and scientific papers
Optimizing ligand structure for low-loading and fast catalysis for alkynyl-alcohol and-amine cyclization
Stubbs, James M.,Bridge, Benjamin J.,Blacquiere, Johanna M.
, p. 7928 - 7937 (2019)
A series of [Ru(Cp/Cp?)(PR2NR′2)(MeCN)]PF6 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. The effect of the 1° coordination sphere structure on catalyst performance was evaluated. Steric bulk around the metal centre was a key feature to achieve rapid catalysis at low temperatures. The catalyst [Ru(Cp)(Pt-Bu2NPh2)(MeCN)]PF6 gave a turnover number that was >1 order of magnitude more active than previous catalysts in the cyclization of the benchmark substrate 2-ethynylaniline. This catalyst is tolerant of a diversity of functional groups and is competent at the formation of various substituted indoles.
