Ni-catalyzed Cyclotrimerization Of Alkynes To Prepare Polysubstituted Benzenes

Alkyne conversion reactions are important synthetic basis in organic synthesis reactions and an important way to achieve molecular diversity.As a class of inexpensive,readily available and versatile structural units,alkynes can be converted into other important intermediates through various chemical reactions due to the special properties of their unsaturated bonds.The most direct and effective method for substituted benzene ring derivatives is an important cornerstone for the synthesis of new materials and bioactive compounds with high atom economy.Transition metal catalysts have great application value in such reactions.In the existing reports in this field,the preparation of polysubstituted benzene rings is mainly achieved by the trimerization of terminal alkynes or some simple internal alkynes.However,the synthesis of polysubstituted benzene rings by the polymerization of aromatic ester internal alkynes is rarely reported,so it is of great significance to develop a catalytic system to realize such reactions.In this dissertation,aromatic ester-based internal alkynes were synthesized in moderate to good yields through the coupling reaction of aryl halides with terminal alkynes.Based on this,the reaction conditions for synthesizing polysubstituted benzene ring products through aromatic ester internal alkynes were explored.Through the investigation of catalysts,reaction ligands,additives and other conditions,the nickel-catalyzed tri-synthesis of such alkynes was realized.In the polymerization reaction,a series of polysubstituted benzene products were synthesized with high yield and regioselectivity.Various functional groups such as trifluoromethyl,cyano,various halogens,methyl groups with electron-donating effects,etc.,were used in the reaction.are well compatible.Furthermore,this reaction enables gram-scale preparation.The whole reaction steps are simple and easy to operate,and the reaction conditions meet the requirements of green chemistry.In most cases,1,2,4-trisubstituted benzene is used as the main product.This reaction adds new content to the study of polysubstituted benzene ring derivatives,enhances the richness of polysubstituted benzene ring compounds,promotes the development of aromatic ring compounds,and provides a new strategy for the construction of polysubstituted benzene rings;another On the other hand,the proposal of this catalytic system has developed a new role of transition metal Ni catalysts and promoted the development of nickel catalytic chemistry.