Lewis Acid-controlled Tandem Cyclization Of 1,3-enynoates For The Synthesis Of 4-thioetherified Pyran-1-(5H)-one Derivatives

Pyranone scaffold,a six-membered lactone,widely exists in many natural products and fine chemical products with physiological or pharmacological activities.It can also be used as synthetic organic intermediate or universal starting material in chemistry and medicine chemistry.Sulfur is one of the most important elements in living systems in the form of proteins and amino acids.Organosulfur compounds are ubiquitous in many natural and non-natural products,which can be used in agricultural chemistry,pharmaceuticals,pesticides,medical chemistry,materials science,etc.Therefore,sulfur-containing organic molecules play an important role in synthesis chemistry,pharmaceuticals,and materials science.Among them,the trifluoromethylthio group is one of the key structural units,which is widely found in medicines and agricultural chemicals.In addition,aryl sulfide building blocks are commonly found in various natural products,biologically active compounds and medicines.Aryl sulfide is also in common used as agricultural chemicals and functional materials.Consequently,it is important to synthesize thioetherified pyranone derivatives.Based on our previous research on the tandem cyclization functionalization of 1,3-enynyl compounds,this paper mainly studies the tandem cyclization a nd thioetherification of 1,3-enynoates via introduction of trifluoromethylthio gr oup and aryl sulfur building block.The first chapter mainly introduces the routes for the construction of pyranone scaffold and the transformations of pyranone derivatives.The second chapter investigates the Lewis acid Bi Br₃/BF₃·Et₂O promoted t he electrophilic trifluoromethylthiolation reaction of 1,3-enynoates using trifluor omethylthioaniline as electrophile to synthesize various 4-trifluoromethylthio pyr anone derivatives.This method has good applicability to various functional gro ups and can provide corresponding products with medium to excellent yields.The third chapter studies the Lewis acid Al Cl₃promoted arylthiolation reaction of 1,3-enynoates.This reaction provides 4-aryl thioetherified pyranone derivatives via construction of C-S bonds using N-arylsulfanylsuccinimides as electrophiles.The reaction features:simple conditions,wide range of substrates,and high yields.In addition,some 4-aryl thioetherified pyranone derivatives show fluorescence properties,and the product with electron-withdrawing group（p-nitro）shows significant red-shift,and the largest emission wavelength is 530 nm.Diels-Alder cycloaddition reaction of pyranone derivatives with acetylenedecarboxylic acid dimethyl ester has been developed under high temperature to generate high-value dimethyl phthalates in good yields.