EFFICIENT SELECTIVE REDUCTION OF AROMATIC NITRO-COMPOUNDS AFFORDING AROMATIC-AMINES UNDER CO/H2O CONDITIONS CATALYZED BY AMINE-ADDED RHODIUM-CARBONYL COMPLEXES

Remarkably high catalytic activities for the reduction of aromatic nitro compounds affording aromatic amines using CO (1 atm) and water at room temperature were exhibited by using amine-added rhodium carbonyl complexes (Rh(CO)2(acac), Rh4(CO)12, and Rh6(CO)16) in 2-methoxyethanol or diglyme (diethylene glycol dimethyl ether) containing a 5 equiv NaOH aqueous solution. The reduction proceeded not only with high catalytic activities, but also with remarkably high nitro-group selectivities, as exhibited in the case of 1-nitroanthraquinone affording 1-aminoanthraquinone, without any other unsaturated groups, such as C = O, being reduced. The T.O.F. (turnovers/time) of 1776 mol-cat-1 h-1 (296 g-atom Rh-1 h-1) was attained for the reduction of p-nitroanisole yielding p-anisidine using Rh6(CO)16-1,8-bis(dimethylamino)-naphthalene catalyst.