Study On The Synthesis Of Novel Spiro Dihydrofurans And Tetra-substituted Furan Derivatives

Both furan and indole derivatives are important heterocyclic compounds,which have a wide range of biological activities and are also important building blocks of organic synthesis.Their synthesis methods have always been one of the research hotspots.In this paper,two aspects were mainly studied.First,the Cu OTf/Tf OH-catalyzed cascade reaction of conjugated alkynoenone is explored to synthesize a new spiro dihydrofuran.Second,in the presence of Ag Sb F₆ and K₂CO₃,the reaction of conjugated ene-yne-ketones and indole to synthesize tetrasubstituted3-indolylfuran derivatives is investigated.The thesis is divided into three parts to discuss.In chapter one,the literatures on the synthesis and reaction of furan compounds,and on the reactions of conjugated alkynoenone and indole compounds are reviewed.In chapter two,the method of spiro dihydrofuran synthesis from conjugated ene-yne-ketones is discussed.The optimal conditions for the synthesis of spiro dihydrofuran derivatives are as follows:the use of Cu OTf（10 mol%）and Tf OH（3 equiv.）as a catalyst,anhydrous DCE as solvent at 25 ^oC under N₂.For most of ene-yne-ketones,the desired products were provided in 32-83%yield.The advantages of this method include mild reaction conditions,simple operation and easy availability of raw materials.In chapter three,the synthesis of functionalized 3-（furan-3-yl）-1H-indole from acetylene ketene and indole is studied in the presence of Ag Sb F₆ and K₂CO₃.The optimal conditions for the synthesis of the tetra-substituted indolylfuran derivatives are as follows:in the first step,at room temperature and under nitrogen protection,Ag Sb F₆（10 mol%）as a catalyst and anhydrous DCE as solvent;in the second step,K₂CO₃（2equiv.）,anhydrous acetonitrile as solvent,reflux.The synthesis of the functionalized polysubstituted furan derivatives is achieved from simple raw materials.On the basis of above method,a strategy for the synthesis of new substituted furan heterocyclic compounds is provided.