Carbo-/Heterocyclization Reactions Of Propargylic Alcohols With Ketene Dithioacetals

Carbon/heterocyclic ring as a key structural element widely found in natural products,synthetic drugs, dyes, and organic functional materials, the development of a new cyclization,has been the core content of organic synthetic chemistry research. Preparation of newmulti-functional organic synthesis and thus build the required sub-ring system, is developinginto a new ring main policy response. Therefore, creatively designed and preparedmulti-functional, multi-site reactions in organic synthon is an important part of organicsynthesis research. Alkyne and ketene dithioacetals are representative organic synthons, overa hundred years of research history. Organic chemists use structural features of both stereoand replace factors, electronic effects and other factors to develop a new strategy for thesynthesis of a number of carbocyclic and heterocyclic compounds, forming a distinctivesynthesis methodology. If you can both "fusion" into a new organic synthon (make structuralfeatures of both alkyne and ketene dithioacetals), and the resulting synthon will haveimportant applications.Our group has been working alkyne chemistry research, the 'functionalized alkyne'research new ideas based on years of research experience. As a representative of a class of'functionalized alkyne', propargyl alcohols in the presence of lewis acid easy to producealkynyl carbocation can be reacted with a nucleophilic species to produce new 'functionalizedalkyne'; Meanwhile, alkynyl carbocations rearrangement can generate allenic carbocations. ?-carbonyl ketene dithioacetals is easy to prepare a synthetic intermediate, the ?-position has astrong nucleophilicity to react with the electrophilic species. Based on the responsecharacteristics of propargyl alcohols and ketene dithioacetals, we creatively combine both bybuilding alkynyl/ketene dithioacetals 'fusion' synthetic intermediates, further intramolecularcyclization occurs, or to direct intermolecular cyclization reaction to provide a new methodfor the synthesis of a number of important carbo/heterocyclic compounds. The thesis isdivided into five chapters.The first chapter introduces the propargyl alcohols compound used in organic synthesis.The second chapter, the significant advances in the chemistry of ketene dithioacetals inrecent years are reviewed.The third chapter of the paper topic.The IV chapter, we have developed a conceptually new strategy to synthesizecyclopentadienes by BF3Et2O-catalyzed regiospecific [3+2] cycloaddition of propargylic alcohols and ?-oxo ketene dithioacetals. The ?-oxo ketene dithioacetals were for the first timeapplied to carbocyclic synthesis as polarized alkenes. A mechanistically novel1,4-alkylthioshift was observed in the ring-closure process. The unique substitution pattern ofcyclopentadienes facilitated an unusual dethiolation Diels–Alder reaction with maleimides,affording a new small organic fluorescent dye molecules, with ease a lot of preparation, easeof structural modification, etc., and has excellent photophysical properties.Chapter V, the containing ketene dithioacetals 'functionalized alkyne' were efficientlyconstructed through a coupling reaction of propargyl cabocations from propargylic alcoholswith ketene dithioacetals. Further the use of such synthons intermolecular or intramolecularcyclization reaction, we finally obtain several important compounds, such as polysubstitutedpyrroles, thiophenes, dihydrothiophenes and benzo[f]-1-indanones and so on.