A simple, one-pot, phosgene-free approach to a series of unsymmetrical 2-pyridyl ureas
starting from 2-aminopyridine and various aromatic amines is reported for the first
time. The procedure employs inexpensive selenium as the catalyst, and carbon monoxide
(instead of phosgene) as the carbonyl reagent. The products are obtained in moderate
to good yields via selenium-catalyzed oxidative cross-carbonylation of the substrate
amines in the presence of oxygen. The selenium functions as a phase-transfer catalyst
and can be recovered easily and reused without any significant degradation of its
catalytic activity.
Key words
carbonylation - selenium - carbon monoxide - 2-pyridyl ureas - 2-aminopyridine
