Study On Borylation Reaction Catalyzed By N-Heterocyclic Carbene And Transition Metal

From the Suzuki reaction,cross-coupling reactions involved boric acid derivatives catalyzed by transition metals have became the most important and widely used methods of boronation.Arylboronic acids and their derivatives are active in the fields of materials science,medicinal chemistry,organic synthesis and pharmaceutical synthesis.Traditional methods depend on the reaction of aryllithium or Grignard reagent with trialkylborates,which usually required harsh conditions and has narrow functional group compatibility.The transition metal catalyzed boronation reaction is favored by chemists because of mild reaction conditions,selectivity single,and good functional group tolerance.This paper were divided into three parts:The first part briefly reviewed the development and synthesis ways of carbene ligands and the research progress in synthesis of aryl boronic acids under metal catalysis.The second part mainly introducesd the research about the borylation of2-phenylpyridine at the 2'-position catalyzed by N-heterocyclic carbene and ruthenium at room temperature.Six N-heterocyclic carbene ligands were synthesized and further combined with transition metals to form the catalytic system.The boronation of 2-phenylpyridine was successfully carried out at room temperature by using carbene and transition metal catalyst system to generate the product 2-[2-?4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl?phenyl]pyridine.The functional group of the reaction had good compatibility,the synthesis methods of ligands were simple,the raw materials were easy to obtain,the reaction conditions were mild,and the conversion of final product could be carried out easily.The structure of the products were confirmed by ¹H NMR,¹³C NMR and HRMS.The third part introduced the study on the boronation of indole catalyzed by N-heterocyclic carbene and transition metal.The boronation of indole was investigated.After a large number of experimental studies shown that the catalytic system not only produced boride products but also produced reduced products,even two signal-substituted products during the reaction process,and the mixed products cannot be separated.We deeply and thoroughly analyzed the reasons for the failure of the experiments,try to find the possible conclusions for the failure of the experiments,propose feasible improvements and follow-up research ideas,and eliminate a pathway for follow-up researchers.