Selective Construction Of Fluorinated Allenes And Pyrans Based On β-trifluoromethyl-1,3-enynes

Fluorinated compounds are widely used in biomedicine,pesticides,materials,chemicals and organic synthesis.β-trifluoromethyl-1,3-enynes,as direct sources of fluorine-containing derivatives,have been widely concerned by chemists because of their unique reactivity.In this thesis,β-trifluoromethyl-1,3-enynes are selected as substrates,and different types of fluorine-containing compounds are constructed based on the selective reaction of active end-ene sites with different carbon nucleophiles.Firstly,the synthesis method of fluorinated allenes is constructed withβ-trifluoromethyl-1,3-enynes and malononitrile as reaction substrates.The reaction conditions are optimized by investigating the factors of reaction temperature and time,base and solvent type.On this basis,the broad spectrum of the reaction is further studied by expanding the structure ofβ-trifluoromethyl-1,3-enynes.The structures of the products are characterized by nuclear magnetic resonance hydrogen spectrum,carbon spectrum,fluorine spectrum.The results show that in the catalytic system of Ag NO₃/K₃PO₄,β-trifluoromethyl-1,3-enynes and malononitrile as raw materials can be synthesized with a series of allenes containing trifluoromethyl and cyanogroup active structural units,the constructed synthesis method has good functional group tolerance.In addition,the reaction mechanism of the synthesis method is speculated,and the allenes containing ibuprofen skeleton is constructed and synthesized with the constructed method in high yield.Secondly,the synthesis of monofluorinated 4H-pyran derivatives was constructed by the series reaction of 1,3-dicarbonyl compounds with ring and chain structures andβ-trifluoromethyl-1,3-enynes.The reaction conditions are optimized by investigating the factors such as reaction temperature and time,base and solvent type.On this basis,the broad spectrum of the reaction ofβ-trifluoromethyl-1,3-enynes with acetylacetone,ethyl acetoacetate,5,5-dimethyl-1,3-cyclohexanedione was further studied by expanding the structure.The structures of the products were characterized by nuclear magnetic resonance hydrogen spectrum,carbon spectrum,fluorine spectrum.The results showed that 33 monofluorinated 4H-pyran derivatives with enynes structure were obtained with moderate to high yields by the proposed method.The reaction mechanism may go through nucleophilic attack,β-F elimination,enol tautomic nucleophilic cyclization andβ-F elimination again.