Domino Reaction Induced By C-S Bond Cleavage Of Thioisatins

Benzothiophene and benzothiopyran compounds have good biological activities and unique properties,which are widely used in drug and material chemistry.Therefore,the development of synthetic methods for benzothiophene and benzopyran compounds has attracted wide attention.In this thesis,thioisatins and 2-bromo-1-phenylethan-1-one were used as reaction substrates.The domino reactions between thioisatins and 2-bromo-1-phenylethan-1-one were promoted by inorganic bases and amine,which provided a new synthetic route for the synthesis of benzothiophene fuse nitrogen heterocyclic compounds.1)Firstly,amine-mediate C-S bond cleavage of thioisatins was studied.Reaction of thioisatin and 2-bromo-1-phenylethan-1-one,various benzothiophene fused nitrogen heterocyclic compounds were obtained under catalyst-free conditions.Except for the 2-bromo-1-phenylethan-1-one,3-bromo-1,1,1-trifluoropane-2-one was also used as reaction partner.The most important is water could be used as solvent in some domino reactions.2)In addition,ring opening reaction of thioisatins promoted by inorganic bases was also studied.In this domino reaction,benzothiophene fused pyran and benzothiopyran fused furan derivatives were obtained initiated by nucleophilic substitution reaction of thioanion and bromoacetophenone,and then condensation reaction twice under alkaline conditions.In this domino reaction,one C-S bond was cleavaged and two C-C bonds were formed.It is a simple method to synthesize benzothiophene and benzothiopyran heterocycles3)The mechanism of domino reaction and the selectivity of some reactions were analyzed and explained by DFT theory,and the antitumor activities of some compounds were also in progress.4)A total of 243 new compounds were synthesized.All the compounds were characterized by NMR,HRMS and IR.The solid compounds were determined by melting point and their structures were determined by single crystal diffraction.