Studies On The Clean Synthesis Of 2-substituted Benzothiazoles

2-Substituted benzothiazoles are a class of bicyclic compounds with medicinal value. Several methods for green synthesis of these compounds are discussed. This Master thesis is consisted of two parts. The first one is focus on the synthesis of 2-substituted benzothiazoles in water. The second is focus on the synthesis of 2-substituted benzothiazoles in PEG.In part one, the research progress of synthetic methods for 2-substituted benzothiazoles and recent research progress of organic reactions in aqueous media are reviewed. Then, two methods for synthesis of 2-substituted benzothiazoles are studied as follow: (1) 2-substituted benzothiazoles are synthesized by the condensation of alkyl, aryl, arylformyl aldehydes with 2-aminothiophenol in water; (2) 2-arylbenzothiazole derivatives are prepared by the reaction of 2, 2'-disulfanediyldianiline with aryl aldehydes in aqueous media.In part two, the application of PEG as green reaction media in organic reactions is reviewed. Also, two methods for synthesis of 2-substituted benzothiazoles are studied as follow: (1) 2-hydroxy-1, 2-diarylethanone or 1, 2-diarylethane-1, 2-dione and 2-aminobenzenethiol as substrates for synthesis of 2-aryl benzothiazoles in PEG is studied; (2) 2-Substituted benzothiazoles is synthesized via condensation of 2-aminothiophenol with alkyl and aryl aldehydes in PEG-400 without catalyst.Some advantages of the present methods are simple operation, easy separation, mild reaction conditions and good yields, which provide the new methods for the synthesis of 2-substituted benzothiazoles. It meets the requirements of green chemistry.