A simple iridicycle catalyst for efficient transfer hydrogenation of N-heterocycles in water.
A cyclometalated iridium complex is shown to catalyse the transfer hydrogenation of various nitrogen heterocycles, including but not limited to quinolines, isoquinolines, indoles and pyridinium salts, in an aqueous solution of HCO2H/HCO2Na under mild conditions. The catalyst shows excellent functional-group compatibility and high turnover number (up to 7500), with catalyst loadings as low as 0.01 mol % being feasible. Mechanistic investigation of the quinoline reduction suggests that the transfer hydrogenation proceeds via both 1,2- and 1,4-addition pathways, with the catalytic turnover being limited by the step of hydride transfer.
Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD (UK) http://pcwww.liv.ac.uk/∼jxiao.
Dinesh
D
Talwar
Ho Yin
HY
Li
Emma
E
Durham
Jianliang
J
Xiao
D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006865:Hydrogenation; D007495:Iridium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D056831:Coordination Complexes; D006571:Heterocyclic Compounds; D014867:Water; D007495:Iridium
N-heterocycles; green chemistry; iridium; transfer hydrogenation; water