REGIOSELECTIVE CATALYTIC-HYDROGENATION OF NITROGEN RINGS OF FUSED HETEROAROMATIC-COMPOUNDS WITH AN IRIDIUM-TRIPHENYLPHOSPHINE COMPLEX

Catalytic hydrogenation of fused heteroaromatic compounds, acridine, q uinoline and quinaldine, selectively occurs at the nitrogen containing rings to give 9,10-dihydroacridine, 1,2,3,4-tetrahydroquinoline and 1 ,2,3,4-tetrahydroquinaldine in the homogeneous solution prepared from the reaction of [Ir(COD)(PPh(3))(PhCN)]ClO4 (COD = 1,5-cyclooctadiene) with H-2 (5 atm) at 50 degrees C, while isoquinoline and indole are n ot hydrogenated under the same experimental conditions. In the presenc e of the rhodium analog [Rh(COD)(PPh(3))(PhCN)]ClO4 however, both isoq uinoline and indole are also hydrogenated at the nitrogen containing r ings, which is understood in terms of heterogeneous catalysis by metal lic rhodium powders produced in the reduction of the rhodium compound under the same experimental conditions (50 degrees C, 5 atm of H-2).