Alkali-mediated Ring-opening And Ring-closing Reaction Of α-Ethy Nyl Ketene Dithioacetals To Prepare Multifunctionalized Thiophenes

α-Oxoketene dithioacetals are a kind of important intermediates in organicsynthesis.They can be used in many reactions for their multiple functional groups. With thecontinuous development of science and technology, synthesis of Thiophene and its applicationhas become increasingly important.In the past few years, systematic studies on the ketenedithioacetals and its further applications have been made in our group. Based on the researchachievements our group have made in the past decades, much new work has been developedin this paper. α-Oxoketene dithioacetals converts alkynes for synthesis of thiophene.Thiophene is a kind of important heterocyclic compounds, and its derivatives inpharmaceutical, pesticide, dye, chemical reagent, functional materials, etc a wide range ofapplications. There are two general methods that have been reported in the literature．One isthe direct functionalization of the thiophene ring (usually-metalation or-halogenation).The other is via the annulations reactions of suitably substituted open chain precursors.Thelatter may allow regioselective preparation of the thiophene derivatives and thus represents anattractive，but less developed methodology.Nowadays, the utility of α-oxo ketene-(S,S)-acetals as versatile intermediates in organicsynthesis to build aromatic and heterocyclic rings has been recognized. In recent years,-oxo ketene-(S,S)-acetals compounds and Vilsmeier reagent for its variety of chemicalreaction activity have attracted the chemist’s more and more attention, which have a widerange of applications in organic synthesis, especially heterocyclic synthesis. Developments ofnew basic reactions and new synthetic methods are the basis for the innovation and advanceof organic chemistry.In this thesis, I would like to represent an alkali-mediated ring-opening and ring-closingreaction of to-ethynyl ketene dithioacetals.As a result, multifunctionalized thiophenes weresuccessfully prepared in one-pot and high yields. The method of synthesis multifunctionalizedthiophenes have beed broaden.