Study On C-H Bond Activation Of Diphenylmethane With Ethynylbenzenes Catalysed By Iron Salts

Conversion of carbon-hydrogen bonds to carbon-carbon bonds is one of important and basic research contents in organic synthetic methodology.It is a very efficient strategy to form new C-C bonds through activation and induction of the C-H bonds directly.With the characteristics of atom economy and environmental friendliness,it is one of the research hot-spots in organic chemistry.In the dissertation,the synthesis of halo-alkenes/cis-alkenes by reaction of diphenylmethane with ethynylbenzenes via C-H bond activation promoted by iron salts was reported.Based on the study of literatures widely,methodological characteristics of different types of C-H activation which included the sp2 C-H activation and the sp3 C-H activation in the past decade were reviewed.A direct synthesis of stereo-selective halo-alkenes/cis-alkenes from diphenylmethane and ethynylbenzenes in the presence of iron(?)bromide or chloride as catalyst and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ)as oxidant was developed.15(3-halo-2-ene-1,1,3-triyl)tribenzene derivatives were synthesized in the yield of 41-74%and 8 of them were new compounds.At the same time,a possible mechanism of the reaction was discussed.The reaction conditions were optimized,the optimal reaction conditions were selected as follows:catalyst iron(III)bromide,oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone,solvent chlorobenzene,reaction temperature 50 ?,reaction time 24h,ethynylbenzenes dropped into the reaction system under the atmosphere of nitrogen.cis-configuration of the major alkenes of the cross-dehydrogenation coupling(CDC)reaction was confirmed after debromination of the major products.Even if there were two big groups like benzene in the same side of the double bond,cis-alkenes were still obtained.A new pathway to prepare halo-alkenes and syn-alkenes was developed.