Ureas are useful substructures for herbicide, pesticide, and raw materials of resin. Generally, ureas are synthesized through the condensation of an amine with an isocyanate or the reaction of amines with phosgene or carbon monoxide. Given the limited number of commercially available isocyanates and the toxicities related to the use of phosgene, an alternative environmentally benign and high-throughput synthetic method for the synthesis of ureas is desirable. The utilization of carbon dioxide as a C1 building reagent for the synthesis of ureas has attracted extensive attention because of nontoxic, abundant, and economical characteristics of carbon dioxide. This process, however, requires high temperature and high pressure conditions. Recently, we have developed the one-step synthetic method of imidovanadium(V) compounds by the reaction of amines with oxovanadium(V) compounds. The reaction of the imidovanadium(V) compound with carbon dioxide is expected to afford the corresponding isocyanate. From these points of view, we embarked upon the catalytic synthesis of ureas through the oxovanadium(V)-catalyzed carbon dioxide activation in the presence of amines. The reaction of phenethylamine with carbon dioxide (ballon) by using oxovanadium(V) catalyst in the presence of diisopropylamine (iPr2EtN) as a base and molecular sieve (MS3A) as a dehydrating agent proceeded well to give the corresponding urea in 93% yield. To explore the validity of this catalytic system, a variety of amines were examined.

Synthesis of ureas by oxovanadium(v)-catalyzed carbon dioxide activation

2019 Spring National Meeting

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