Study On The Catalytic Aerobic Oxidative Couplings For S-N Bond Constructions And Arylthiation

Organic compounds containing S-N bonds and S-C bonds have been found in lots of natural products and synthetic functional molecules.Therefore,it is of great value and significance in pharmaceutical and organic synthetic chemistry to study on the formation methods of S-N bonds and S-C bonds.In this thesis,synthetic methodologys of intermolecular and intramolecular S-N bonds formations have been investigated.Furthermore,phenylthiation of aromatic C-H with sulfonamides was also explored preliminarily.The detailed results are outlined as follows:1.TEMPO-catalyzed aerobic oxidative coupling of thiols and amines for metal-free formation of S-N bondsCatalytic syntheses of organic sulfenamides have great significance and value in bioscience and synthetic chemistry.To establish a versatile and efficient technology for such reactions,an aerobic oxidative coupling method for the formation of S-N bonds has been successfully developed by using TEMPO as a catalyst and O2 as an oxidant.Sulfenamides were produced in up to 99% yield in one-pot syntheses.The reaction showed good tolerance toward various alkylamines and attractive characteristics consisting of simple and efficient system,metal-free catalysis,eco-friendly oxidant and high atomic economy(Scheme 1).2.Reusable cobalt-phthalocyanine in water: efficient catalytic aerobic oxidative coupling of thiols and amines to construct S–N bondsTo establish a mild and green methodology for S-N bonds generation,we successfully developed a new aerobic oxidative coupling of thiols and amines in water,utilizing cobalt(II)phthalocyanine-tetra-sodium sulfonate(Co Pc S)as the catalyst and O2 as the oxidant.Sulfenamides were produced in modest to excellent yields.After the reaction,the products can be easily obtained via filtration and the catalyst within the solution can be recovered and reused without any particular treatment.The mother liquor could be recycled up to 20 times with negligible loss of activity and only a minor decrease of product yield.The reaction can be easily scaled up to 10 grams.The reaction showed attractive characteristics consisting of green and efficient system,mild conditions,simplifying operations and potential industrial application value(Scheme 2).3.Co-catalyzed intramolecular S-N bond formation in water: novel synthesis of 1,2-benzisothiazol-3(2H)-one and 1,2,4-thiadiazoles derivativesAn efficient and versatile Co-catalyzed S-N bond formation in water to synthesize 1,2-benzisothiazol-3(2H)-one and 1,2,4-thiadiazoles derivatives in good to excellent yields was developed.The transformation showed great tolerance with a broad range of substituents.After the reaction,the products can be easily obtained via filtration and the catalyst within the solution can be recovered and reused without any particular treatment.The mother liquor was able to be recycled 6 times with minor loss in product yield.The key benefits of this reaction include a broad scope of substrates,green and efficient system,mild reaction conditions and industrial application prospects(Scheme 3).4.Al Cl3-catalyzed aromatic phenylthiation with sulfenamideA new and simple protocol for Al Cl3-catalyzed phenylthiation of indols or other aryl compounds with sulfonamides has been developed,and the corresponding C-S coupling products were prepared in modest to excellent yields.The transformation showed great tolerance with a broad range of substituents and the use of sulfenamides as sulfur reagents has not been reported.The method provided a new synthetic strategy for the synthesis of aromatic thioethers(Scheme 4).