关键词: 硒催化, 羰基化, 1,3,4-噻二唑-2-氨基甲酸酯, 2-氨基-1,3,4-噻二唑

Abstract: 1,3,4-Thiadiazol-2-ylcarbamates are an important class of heterocyclic compounds with remarkable medical and agromedical applications due to their pharmacological and biological activities such as antimicrobial, antibacterial, and analgesic effects as well as protein kinase CK2 and acetohydroxy acid synthase inhibition effects. In order to develop an economical, eco-friendly and convenient approach to these target compounds, herein, a facile one-pot selenium-catalyzed carbonylation protocol was studied. The optimal reaction conditions were obtained through investigating the effects of main factors on the carbonylation reaction such as reaction temperature, ethanol dosage, pressure and kind of bases. With cheap and readily available nonmetal selenium as the catalyst, carbon monoxide instead of virulent phosgene as the carbonylation reagent, oxygen as the oxidant, the selenium-catalyzed oxidative carbonylation reaction of 1,3,4-thiadiazol-2-amine proceeded smoothly with a series of alcohols especially with those less hindered ones under the optimized conditions in one-pot manner, affording the corresponding products 1,3,4-thiadiazol-2-ylcarbamates in moderate to good yields. Thus, a new economical, eco-friendly and convenient approach to 1,3,4-thiadiazol-2-ylcarbamates featured with simple and readily available catalyst and raw materials, low cost, high atomic economy, one-pot and phosgene-free manners, and no emission of corrosive wastes has been developed. The probable reaction mechanism was also proposed at the end of this paper.

Key words: Selenium catalysis, Carbonylation, 1,3,4-Thiadiazol-2-ylcarbamate, 1,3,4-Thiadiazol-2-amine