Thioetherification Of Pyrazoles And Indoles

Sulfides are not only found in natural organic products,pharmaceuticals,and biomolecules,but also widely used in material science,chemicals,and foods.Therefore,the development of an effective,novel,and simple method for the synthesis of sulfurcontaining compounds is very important and has attracted widespread attention.However,the traditional synthesis of organic sulfides involves expensive metal catalysis,harsh reaction conditions and the formation of many side products.In this thesis,we developed two effective and metal-free methods for the construction of C-S bonds,generating C-4 sulfenylated pyrazolones and 2-iodo-3-arylmercaptoindoles.This thesis contained two parts.In the first part,we investigated HBr-promoted sulfenylation of pyrazolones with N-arylthiosuccinimides as sulfur resources.The corresponding C-4 sulfenylated pyrazolones were synthesized in good to excellent yields.The reaction conditions are mild and the operation is simple.It is worth mentioning that the reaction system can also be expanded to apply to C-3 sulfenylation of 4-hydroxycoumarins.In addition,the N-arylthiosuccinimides we used is a new type of sulfur source with being almost odorless and stable properties.In the second part,we realized the difunctionalization of indoles at C-2 and C-3 position.This reaction used a simple,cheap and easily available thiophenol as a sulfur source,and iodine pentoxide as the iodine source.The reaction might proceed in the following two cascade steps: in the first step,benzenesulfonyl iodide intermediate was formed by oxidation of thiophenol with I2O5.Subsequently,the electrophilic substitution reaction at the C-3 position resulted in the formation of 3-arylthioindole.In the second step,The radical addition-elimination reaction occurred providing 2-iodo-3-arylthioindoles.It is the first time that iodothiolation difunctionzlization of indoles at C-2 and C-3 positions was accomplished.Mild and metal-free conditions are two advantages.