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 sho wed moderate conversion of the substrates to the corresponding diphenylurea s and anilines as major and minor products respectively. The presence of ac idic cocatalysts increased the yield of diphenylurea while in the presence of basic cocatalysts and alcohols, corresponding carbamates were the main p roducts. The maximum yield and selectivity of the carbamate were achieved u sing NaOMe and MeOH as cocatalyst and cosolvent respectively under optimum reaction conditions. A tentative reaction mechanism based on the identifica tion of reactive intermediates was proposed for this carbonylation process. (C) 1999 Elsevier Science B.V. All rights reserved.