A High Yielding, One-pot Synthesis of Substituted Ureas from the Corresponding Amines Using Mitsunobu’s Reagent

Oxovanadium(V)-Catalyzed Synthesis of Unsymmetrical Ureas by Activation of Carbon Dioxide under Ambient Pressure

“…4b,5 Mitsunobu type reactions are often employed for the synthesis of unsymmetrical ureas, wherein a stoichiometric amount of tributylphosphine oxide is produced as a byproduct (Scheme 1b). 6 Recently, Rousseaux and coworkers have reported the synthesis of unsymmetrical ureas via the formation of isocyanates using dimethylsulfonium reagents, but this reaction required multiple steps (Scheme 1c). 7 We have previously succeeded in synthesizing symmetrical ureas from primary amines and carbon dioxide under ambient pressure using a commercially available VO(O i Pr) 3 catalyst.…”

“…However, the previous synthetic approach using carbon dioxide for ureas requires harsh reaction conditions such as a high reaction temperature and a high carbon dioxide pressure . Also, in the case of the one-pot, one-step synthesis of unsymmetrical ureas from amine and carbon dioxide, the selective synthesis of unsymmetrical ureas is difficult because symmetrical ureas are simultaneously produced as byproducts (Scheme a). , Mitsunobu type reactions are often employed for the synthesis of unsymmetrical ureas, wherein a stoichiometric amount of tributylphosphine oxide is produced as a byproduct (Scheme b) . Recently, Rousseaux and co-workers have reported the synthesis of unsymmetrical ureas via the formation of isocyanates using dimethylsulfonium reagents, but this reaction required multiple steps (Scheme c) …”