Visible Light-Catalyzed Ring-Opening Reaction Of Methylene Cyclopropane

Methylenecyclopropane(MCP)is a class of highly strained organic compound,which can be used in the synthesis of bioactive macromolecules.This thesis mainly studies the visible light-catalyzed MCP ring opening reaction with α-bromoketone,[Ph3PCF2H]+Br-and sulfonyl chloride.The main work of this thesis is structured as follows.1.Visible light-catalyzed MCP ring opening and reaction with α-bromoketoneWe have studied the visible light-catalyzed reaction of MCP and α-bromoketone.During the reaction,different substituted MCP could afford different products through the ring-opening-addition or ring-expansion process(Scheme 1).Under visible light irradiation,using fac-Ir(ppy)3 as the photocatalyst,mono-benzene-substituted MCP yielded a series of dihydronaphthalene compounds through the ring-opening followed by ring-closing pathway.However,when the biphenyl substituted MCP were used as substrates,only ring-opening-addition pathway occurred,and bifunctional enone compounds were obtained.We determined the molecular configuration of the products through single crystal diffraction technology,and explored the possible mechanisms of the two pathways through TEMPO capture experiment and BHT inhibition experiment.2.Visible light-catalyzed reaction of MCP ring opening and[Ph3PCF2H]+BrWe found that the selective ring-opening addition and ring expansion of the product can be controlled by changing the structure of MCP.Therefore,we tried to synthesize functionalized CF2H substituted dihydronaphthalene compounds.Under the condition of mono-substituted benzene ring MCP,CF2H free radicals are generated by visible light catalysis[Ph3PCF2H]+Br-,followed by free radical reaction with MCP to obtain ring-closing CF2H substituted dihydronaphthalene compounds.When the substituent of MCP is a biphenyl ring,under the same reaction conditions,a ring-opened bifunctionalized product is obtained(Scheme 2).The molecular configuration was determined by single crystal diffraction technique.3.Visible light catalyzed the reaction of MCP ring opening and sulfonyl chlorideWe explored the use of visible light to catalyze MCP to synthesize sulfone compounds.we synthesized a series of ring-opening bifunctional sulfone compounds using methylenecyclopropane and p-toluenesulfonyl chloride as reaction template substrates,and fac-Ir(ppy)3 as photocatalyst(Scheme 3).This method has good substrate applicability and high reaction yield.When we use methylenecyclopropane substituted with a single benzene ring,the reaction does not occur,and the reaction mechanism research and further applications are being explored.