ORGANOIRIDIUM CATALYZED HYDROGEN ISOTOPE-EXCHANGE - LIGAND EFFECTS ONCATALYST ACTIVITY AND REGIOSELECTIVITY

Several iridium complexes [Ir(cod)L(2)]X (L = phosphine ligand) were u sed as precatalysts for the exchange labeling of a range of model comp ounds with deuterium gas. Complexes with monodentate L (e.g. PMePh(2), PPh(3) and substituted derivatives thereof) catalyzed exchange select ively of hydrogens four bonds away from a coordinative heteroatom in t he substrate, while those with bidentate L (bis(diphenylphosphino)etha ne (dppe) and bis(diphenylphosphino)butane) catalyzed exchange of hydr ogens 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)]BF4 catalyzed the tritium labeling of methyl 6-methoxynaphth-2-ylacetate at C1 and C3.