Research On Light Induced Fuctionalization Of C=C Bond

Functionalization of alkenes is an important method for the construction of carbon-carbon and carbon-heteroatom bond in organic synthesis.It is frequent to use this method for constructing the molecular skeleton of natural product,drug molecule and organic functional materials.As a kind of clean energy,light has the advantages of non-pollution.In view of the importance of functionalization of alkenes,a series of indolone,amides,isoquinolone,isoxazolidine and bis(indolyl)methan were synthesized to explore the application of photochemistry.We realized a UV light-mediated benzoyl acylation of ?,?-unsaturated amide.By application of free radical addition and cyclization reaction with 350 nm ultraviolet light as the light source,economical and stable benzoin as the benzoyl radical source,alkyl ?,?-unsaturated amide as substrates,it achieves the benzoyl indolone derivatives in 27-85% yield.Benzoyl amide derivatives was synthesized in 53-90% yield using aryl ?,?-unsaturated amide as substrates under the same conditions.A series of ?,?-unsaturated amide were prepared to investigate the scope of the reaction.A control experiment by reaction with TEMPO(2,2,6,6-tetramethyl piperidine)as free radical scavenger was conducted,and a possible reaction mechanism was proposed,the benzoyl radical attacked C=C bond and then followed by a intramolecular cyclization.By the application of visible-light induced oxidative quenching strategy,we realized trifluoromethylation of ?,?-unsaturated amide through free radical addition and cyclization reaction.A series of trifluoromethyl indolone derivatives were synthesized in 40-80% yield by using Ru(bpy)3Cl2 as visible light catalyst,CF3SO2 Cl as trifluoromethyl source,K2HPO4 as the base,Blue LEDs as the light source,and alkyl ?,?-unsaturated amide as substrates.Trifluoromethyl amide derivatives were obtained in 45-71% yield with aryl ?,?-unsaturated amide as substrates under the same conditions.Trifluoromethyl isoquinoline derivatives were synthesized in 43-70% yield by using ?,?-unsaturated benzamide as the substrates under the same conditions.The scope of substituted ?,?-unsaturated amide were explored on the influence of the substituent.The control reaction by TEMPO capture experiment showed that the reaction followed a free radical pathway and intramolecular cyclization,which lead to the trifluoromethyl indolone,amides and isoquinolone.A series of alkene and nitrone were prepared and subjected to thephotochemical reaction.The visible-light mediated reductive quenching reaction was explored,leading to a variety of oxazolidine and bis(indolyl)methan derivatives.The photochemical reaction was carried out under the condition of2,4,6-tri-p-tolylpyrylium as visible light catalyst,Blue LEDs as the light source,and nitrones and styrenic olefin as substrates,which led to oxazolidine derivatives in 19-85% yield.Under the same conditions,bis(indolyl)methan derivatives were synthesized in 31-86% yield with nitrone and N-methylindole as substrates.A series of nitrone and alkene with different substituent group were prepared to investigate the scope of the reaction.Alkenes with electron-donating group were more favorable for reaction than the ones with electron-withdrawing group.Fluorescence quenching analyses and showed that alkene could act as reductive quencher during the reaction.Quantum yield experiment demonstrated the chain propagation of the reaction strongly.A plausible reaction mechanism was proposed for the cycloaddition reaction with alkene acting as reducing quencher.