Low-temperature synthesis of tetraalkylureas from secondary amines and carbon dioxide

The reaction of dialkylamines with CO2 giving tetraalkylureas can be performed at 60 degreesC. The reaction requires CCl4, is weakly promoted by DMAN or PPh3, and is not promoted by a Pd catalyst. A two-step procedure, in which dialkylammonium dialkylcarbamate is produced in situ and then reacted with CCl4 and free dialkylamine, gave greater yields of urea than a simple single-stage procedure.