| C-C（sp2）bonds are present in almost all complex organic molecules,whether in molecular skeletons or substituents;there are mainly two types of aromatic rings and carbon-carbon and carbon-heteroatom double bonds,both in maintaining molecular structure and participating in chemical reactions.Extremely important applications can be called the core of organic chemistry.The construction of C-C（sp2）bond-related reactions has a history of more than two hundred years,and related research results have long been used in industrial production,medicine and other industries.Traditional C-C（sp2）bond formation reactions mostly rely on the catalytic reactions of noble metals such as palladium,ruthenium,and rhodium.It has disadvantages such as harsh conditions,troublesome post-processing,and difficulty in catalyst recovery,which limits the use of this type of catalytic reaction to a certain extent.In recent years,cheap metal catalysts have gradually emerged and are equivalent to precious metal catalysts on some occasions.Visible light,as an inexhaustible energy source,has also been widely used in industrial production to synthesize various biologically active molecules.C-C（sp2）bond reactions catalyzed by cheap transition metals have gradually become a research hotspot in recent years.In this dissertation,1,6-diacetylene compounds and substituted alkynes are used as substrates,under the co-catalysis of visible light catalyst Ir[ppy2dtbbpy]PF6and nickel complex to explore[2+2+2]cycloaddition reactions,and a series of substituted benzenes have been synthesized.27 kinds of compounds were synthesised,and the yield is up to 76%.Mechanism verification experiments show that the reaction is a visible light-transition metal synergistic catalytic reaction,through the metal-1,6-diyne five-membered ring intermediate and then alkynyl addition to obtain substituted benzene ring compounds.The reaction conditions are mild and the tolerance of functional groups is good,which enriches the methodology of aromatization reactions.Based on the theory of electron donor-acceptor complex（EDA）,this dissertation designs and uses cobalt complex as a single metal catalyst,N-hydroxyphthalimide carboxylate（NHP ester）and styrene compounds as the substrate,Hantzsch ester was used as a reducing agent to synthesizeβ-substituted styrene compounds under the action of visible light.There were 14 kinds of Heck reactions,and the olefin double bond configuration selectivity E:Z>20:1.This reaction does not require a photocatalyst,nor does it require a precious metal catalyst such as palladium.Mechanism verification experiments show that the reaction is a typical EDA reaction.This is the first time that the EDA reaction has been applied to the study of the Heck reaction,and it provides a new and effective way for the synthesis ofβ-substituted styrene compounds. |
