The electrochemical reduction of 1,3-dialkylimidazolium ionic liquids gave the corresponding N-heterocyclic carbenes that, after reaction with elemental sulfur and ultrasound irradiation, yielded 1,3-dialkylimidazole-2-thiones in very high yields. The reaction is very clean, produces no side-products and avoids the use of any other added reagent.
Feroci, M., Orsini, M., Inesi, A. (2009). An Efficient Combined Electrochemical and Ultrasound Assisted Synthesis of Imidazole-2-Thiones. ADVANCED SYNTHESIS & CATALYSIS, 351, 2067-2070.