Reductive carbonylation of nitroaromatics using RhA(CO)2

The investigation of the catalytic activity of RhA(CO)(2) (HA = anthranilic acid) towards the reductive carbonylation of nitroaromatics in DMF medium under high Po (8.0 X 10(3) kNm(-2)) at 140 degrees C without cocatalyst showed moderate conversion of the substrates to the corresponding diphenylureas and anilines as major and minor products respectively. The presence of acidic cocatalysts increased the yield of diphenylurea while in the presence of basic cocatalysts and alcohols, corresponding carbamates were the main products. The maximum yield and selectivity of the carbamate were achieved using NaOMe and MeOH as cocatalyst and cosolvent respectively under optimum reaction conditions. A tentative reaction mechanism based on the identification of reactive intermediates was proposed for this carbonylation process. (C) 1999 Elsevier Science B.V. All rights reserved.