Studies On The Synthesis Of Thiocarbamates By Selenium-Catalyzed Carbonylation

The purpose of this thesis is to explore a creative method for the synthesis of thiocarbamates. Using cheap and facile selenium as catalyst, carbon monoxide as carbonylation agent, carbonylation of thiols or aryl thiols with aniline and with nitroarenes has been studied systematically and realized for the first time. The corresponding mechanisms of the reactions have also been discussed during the synthesis process of a series of thiocarbamates.Firstly, the oxidative carbonylation of aniline with thiols mediated by stoichiometric selenium has been investigated. The reaction can proceed well at ambient temperature and atmospheric pressure, to afford the target products in moderate to good yields. After the reaction, selenium can be easily separated from the reaction mixture and can be recycled without any loss of its reactivity.Then the selenium-catalyzed oxidative carbonylation of aniline with thiols has been studied. The corresponding thiocarbamates can be synthesized directly in one step through the oxidative carbonylation of aniline with thiols in the presence of carbon monoxide catalyzed by selenium. Consequently, the reaction approachs are shortened and the consumption of selenium is reduced greatly.In order to broaden the types of the reaction, we have also studied and realized the selenium-catalyzed redox carbonylation of nitroarenes with thiols under pressurized carbon monoxide condition systematically. We succeed in synthesizing a series of thiocarbamates via optimizing reaction conditions.From the view point of application, it is of great importance without fail to reduce the reaction conditions from high pressure to atmospheric pressure. Therefore we studied the redox carbonylation of nitroarenes with thiols at atmospheric pressure in detail and succeeded in reducing the high reaction pressure to atmospheric pressure 。 Consequently, a new one-step approach to thiocarbamates was exploited via selenium-catalyzed carbonylation of nitroarenes with thiols at atmospheric pressure.Lastly, on the base of literature and experiments, we put some superficial understandings on their reaction mechanisms.