Arylation And Sulfone Reactions Involving Arylazosulfones

Aromatic rings and sulfonyl compounds are two important organic molecular skeletons.They are useful building blocks of natural products and drug molecules with biological activity.Therefore,arylations and sulfonations have drawn a great deal of attention from the organic synthetic chemists and medical scientists.In the past few decades,a series of compounds containing aryl and sulfonyl groups have been synthesized by organic chemists.However,these synthetic methods often require metal catalysis,cumbersome experimental procedures,relatively harsh reaction conditions and narrow substrate scopes.Therefore,it is of great significance to develop a simple,green and efficient method to construct aryl and sulfonyl compounds.Arylazo sulfones are colored and bench stable compounds,which could generate aryl radical and sulfonyl radical along with the release of N₂ through the homolytic cleavage of C-N and S-N bonds under visible-light irradiation or heating conditions.Therefore,arylazo sulfones can be used as a reagent for arylations and sulfonations.In this thesis,we synthesized a series of unsymmetrical sulfoxides,β-oxo sulfones and sulfonylatedγ-butyrolactams through the arylations or sulfonations of arylazo sulfones.The detailed description is demonstrated as follows:1.A catalyst-free visible light-initiated oxidative coupling strategy of arylazo sulfones with thiols was developed to synthesize unsymmetrical sulfoxides under air.By using dioxygen as the oxidant and visible light as a clean energy source,this reaction could proceed smoothly at room temperature.The method met the requirements of green synthetic chemistry and provided a green synthetic method for the synthesis of unsymmetrical sulfoxides.2.A facile and catalyst-free protocol was developed for the construction ofβ-oxo sulfones through visible light-induced oxysulfonylation of alkenes/alkynes with arylazo sulfones and dioxygen in air.β-oxo sulfones can be easily synthesized through visible light-induced oxysulfonylation of alkenes with arylazo sulfones at room temperature under air.When oxysulfonylation of alkynes with arylazo sulfones and dioxygen was performed at 50℃,β-oxo sulfones could be obtained in moderate to good yields.These two methods provided a simple,efficient and green synthetic strategy for the synthesis ofβ-oxo sulfones without the use of any metals or photocatalysts.3.A catalyst-and metal-free method for the selective cyclization of arylazo sulfones and 1,6-enynes to synthesize sulfonylatedγ-butyrolactams was developed in air.Various substituted sulfonylatedγ-butyrolactams were synthesized under mild conditions in the absence of additives such as transition metals,acids and bases.This reaction provided a novel and green synthetic route for the construction of sulfonylatedγ-butyrolactam compounds.