Electrochemical Cross-Dehydrogenative Coupling Access To Thiazole Derivatives And Decarboxylation Coupling Access To Arylacetylenic Sulfones

Traditional organic synthesis methods have many advantages such as reliability,and also got great advances.However,the shortcomings are apparent,such as extra additives,transition metals,tedious work-up procedures,harsh reaction conditions with high temperatures and long reaction hours.The electrochemical methods will play an increasingly important role in organic synthesis with mild conditions and higher atomic economy.In this thesis,we mainly studied the electrochemical method of synthesis of thiadiazole and benzoisothiazole derivatives under undivided electrolytic conditions via oxidation dehydrogenation of N-S bond coupling.In addtion,an efficient decarboxylative sulfonylation of arylacetylenic acids with sodium arylsulfinates has been achieved by electrochemical decarboxylation coupling reaction.This thesis is consist of three partsPart one:One-pot electrochemical oxidation dehydrogenation coupling reaction access to 3,5-disubstituted 1,2,4-thiadiazoleswe prepared the imidoyl thiourea as substrates by the reaction of amidine and phenyl isothiocyanate,carbon rods as the cathode,platinum plate as the counter electrode,ⁿBu₄NI as the electrolyte,and acetonitrile as the solvent in an undivided cell.A variety of 3,5-disubstituted 1,2,4-thiadiazole with excellent yields were obtained at a constant current of 20 m A for 3 h at room temperature under undivided electrolytic conditions.Part two:Electrochemical oxidation dehydrogenation coupling access to2-phenylbenzo[d]isothiazoleWe used 2-mercapto-N-phenylbenzothiazoles as substrates,carbon rods as the cathode,platinum plate as the counter electrode,ⁿBu₄NBr as the electrolyte,acetonitrile as the solvent in an undivided cell,a series of 2-phenylbenzoisothiazoles derivatives were obtained at room temperature for 1 h at a constant current of 20 m A under undivided electrolytic conditions.Part three:Electrochemical decarboxylation coupling access to arylacetylenic sulfones.We used 3-phenylpropiolic acid and sodium benzenesulfinate as substrates,carbon rod as the anode of the electrolytic cell,platinum plate as the counter electrode,ⁿBu₄NBF₆ as the electrolyte,acetonitrile and water as mixed solvents in an undivided cell,at room temperature.A variety of arylacetylenic sulfones were obtained in a high yield at a constant current of 20 m A for 2 h under undivided electrolytic conditions.