Study On Late Functional Group Of Pyridine Salts And Sulfur Salts

In the course of the development of chemistry,late-stage functionalization of sulfonium salts and pyridinium salts has been a hot topic in chemical research.Studying these organic salts can help people understand their physical and chemical properties and the construction of new chemical bonds such as C-C,C-B and C-S bonds.In recent years,the late functionalization of sulfonium salts and pyridinium salts has made great progress,which has had a profound influence on the pharmaceutical and food industries,but it also faces many difficulties and challenges.Since the late-stage functionalization reaction of such compounds generally needs to be carried out under harsh reaction conditions,it is particularly necessary to develop a more greener and more efficient method.1.Defluorinated alkylation of trifluoromethylolefin by photoinduced EDA complexesThe development of modern medicine is inseparable from the development of chemistry.Gem-difluoroalkenyls,as common organic modules in drug synthesis,can serve as bioisosteres of carbonyl functional groups.The introduction of gem-difluoroalkenyl can improve the metabolic stability and biological activity of drug molecules,and plays a pivotal role in the later modification of drug molecules.However,the existing synthesis methods generally require the use of expensive transition metal catalysts or photocatalysts,and it is very important to explore a milder synthesis strategy.We developed an efficient method for the synthesis of gem-difluoroalkenes by in situ generation of electron donor-acceptor(EDA)complexes via Hantzsch esters and Katritzky salts,followed by generation of alkyl radicals via photoexcited single-electron transfer.This high active alkyl radical intermediate was captured by a-trifluoromethylalkene,and undergoes a defluoroalkylation process to generate the corresponding gem-difluoroalkene product.In addition to the absence of photocatalysts and transition metals,these transformations show strong functional group tolerance,providing a convenient and efficient method for subsequent modification of biological anpharmaceutical-relateded molecules.2.Base promoted the synthesis of vinyl sulfidesSulfur-containing skeletons are widely found in natural products,pesticides,and organic functional molecules.Sulfur-containing compounds generally possess various excellent biological activities and optical properties.Among them,vinyl sulfide occupies an important position in sulfur-containing compounds,and many drug molecules contain vinyl sulfide molecular fragments.However,the traditional synthesis method of vinyl sulfide has relatively harsh conditions,generally requiring conditions such as transition metal catalysis,high temperature,and high pressure.We developed a novel protocol to achieve base-promoted conversion of sulfides to vinyl sulfides under transition metal catalyst conditions.In this reaction,the mild reaction conditions avoid the use of metal catalysts,high pressure gases,and high reaction temperatures.This reaction has good compatibility with various common functional groups such as ether,halogen,naphthalene,thiophene,etc.3.Base promotes the synthesis of tetrahydrothiophene compounds by the Stevens rearrangement of sulfur saltsSulfur-containing heterocyclic compounds are widely used in the fields of medicine,pesticides,and materials,among which tetrahydrothiophene and its derivatives are widely found in natural product molecules and drug biomolecules.Based on the important position of tetrahydrothiophene molecules in the preparation of new drugs and practical industrial production,this type of molecular skeleton has become a star structural unit in the field of organic synthesis.In the past few decades,it has attracted many organic chemists and biological scientists,scholars’ focus.However,the synthetic strategies for tetrahydrothiophene that have been developed usually require multi-step synthesis.We developed a new protocol to realize the base-promoted Stevens rearrangement of sulfur salt compounds to the corresponding tetrahydrothiophene and its derivatives under no transition metal catalysis conditions.The reaction conditions are mild and do not require high temperature and transition metal catalysts,which provides a new route for the synthesis of tetrahydrothiophenes.