?The cyanomethyl anion/carbon dioxide system: an electrogenerated carboxylating reagent. Synthesis of carbamates under mild and safe conditions?

Carbamates are prepd. electrochem. from amines, carbon dioxide and alkylating agents, avoiding the use of isocyanates or phosgene. Electrolysis of solns. of tetraethylammonium perchlorate in acetonitrile provides a mixt. of cyanomethyl anion and 3-aminocrotonitrile anion; bubbling CO2 into the soln. followed by addn. of amines and subsequent addn. of alkylating agents such as Et iodide provides carbamates in 19-96% yields. The use of other solvents such as DMF gives no carbamate products; when electrolysis of the acetonitrile-tetraethylammonium perchlorate mixt. is not carried out before addn. of amines and carbon dioxide, no carbamates are formed. The use of electrolytes other than tetraethylammonium perchlorate gives reduced yields of carbamates. Arom. amines give lower yields of carbamates than alkyl carbamates.