N-heterocyclic carbomethoxylation catalyzed by ionic liquids in the presence of dimethyl carbonate

A procedure for the synthesis of N-heterocyclic carbamates from N-heterocycles and dimethyl carbonate catalyzed by ionic liquids was investigated. [Bmim]OH was found to be the most active catalyst among the applied ionic liquids. Effects of the amount of ionic liquid, reaction temperature and the reusability of ionic liquid were also investigated. Ninety six percentage yield and 100% selectivity were obtained under the optimal conditions when using indole as a reactant. Additionally, [Bmim]OH can be reused at least up to four times without any decrease of activity. The possible reaction mechanism was discussed based on the reaction results.