Phosgene-free synthesis of N-aryl-N'-4-pyridinylureas via selenium-catalyzed oxidative carbonylation of 4-aminopyridine with aromatic amines

Abstract

A facile, phosgene-free approach with high atom economy has been developed for the synthesis of N-aryl-N′-(4-pyridinyl)ureas. With cheap selenium as the catalyst, carbon monoxide (instead of phosgene) as the carbonyl reagent, N-aryl-N′-(4-pyridinyl)ureas can be obtained in a one-pot manner mostly in moderate to good yields via oxidative cross-carbonylation of 4-aminopyridine with a variety of aromatic amines in the presence of oxygen under atmospheric pressure. The mechanism for the synthesis of N-aryl-N′-(4-pyridinyl)ureas is also proposed.