ORGANOIRIDIUM CATALYZED HYDROGEN ISOTOPE EXCHANGE : LIGAND EFFECTS ON CATALYST ACTIVITY AND REGIOSELECTIVITY

Abstract Several iridiu complexes [Ir(cod)L 2 ]X ( L = phosphine ligand) were used as precatalysts for the exchange labeling of a range of model compounds with deuterium gas. Complexes with monodentate L (e.g. PMePh 2 , PPh 3 and substituted derivatives thereof) catalyzed exchange selectively of hydrogens four bonds away from a coordinative heteroatom in the substrate, while those with bidentate L (bis(diphenylphosphino)ethane (dppe) and bis(diphenylphosphino)butane) catalyzed exchange of hydrogens both four and five bonds away from a coordinative heteroatom. At heavier loadings, some monodentate complexes also catalyzed five-bond labeling of some substrates. [Ir(cod)(dppe)]BF 4 catalyzed the tritium labeling of methyl 6-methoxynaphth-2-ylacetate at C1 and C3.