Selective formation of unsymmetric ureas by selenium-catalyzed oxidative-reductive carbonylation with CO

A series of unsymmetric ureas containing substituted groups have been synthesized via selenium-catalyzed selective oxidative-reductive carbonylation of amines and nitro compounds with CO instead of phosgene in one-pot reaction. These catalytic reactions are important from both synthetic and industrial points of view, because not only the reactions can be proceeded with high selectivity of higher than 99% towards desired unsymmetric ureas, but also there exists a phase-transfer process of the selenium catalyst in the reaction, so that the after-treatment of the catalysts and products from the reaction systems can be easily separated by simple phase separation. (C) 2002 Elsevier Science B.V. All rights reserved.