Metal-Free Ortho-C-H Bond Borylation Of Carboxylate Thiophenolate And Arylcarbonitrile-Carbon-Cyanide Borylation

Compared with traditional organometallic reagents,organoboron compounds have better stability and functional group compatibility,and are easy to diversify and transform.It is an important organic synthesis intermediate.Organoboron compounds can participate in a series of C-C bonds and C-X bonds.It is widely used in chemical,pharmaceutical and material fields.Aryl boronate is one of the most commonly used organic boronate compounds in organic synthetic chemistry.Due to the rarity of boron compounds in nature,its acquisition mainly depends on chemical synthesis,and the synthesis methods mainly include aryl metal reagents and electrophiles.Substitutional borylation of reagents and borylation of aromatic hydrocarbons.Thiophenols and arylcarbonitrile are two important organic compounds that are widely used in organic synthesis reactions.There are some reports on the synthesis of aryl boronic esters using ortho-carbon-hydrogen bond borylation of thiophenol derivatives and arylcarbonitrile carbon-cyanide boronization reactions,but most of these reactions rely on transition metal catalysis.Most of the catalysts used are designed and synthesized by complex modification,have complex structures,are difficult to obtain and are expensive,which limits their application and development.The current reports of metal-free carbon-carbon bond and carbon-hydrogen bond boronation have been widely favored for their prominent environmental-friendly advantages,which are more in line with the concept of green chemistry and become a better alternative to metal catalytic systems.Based on the requirements of cost reduction and environmental friendliness,the development of metal-free ortho-carbon-hydrogen bond borylation of thiophenol derivatives and arylcarbonitrile carbon-cyanide borylation has important scientific significance and practical value.In this paper,the transition metal-catalyzed and metal-free arene-directed carbon-hydrogen bond borylation,as well as the arylcarbonitrile-carbon-cyanide bond activation and borylation reactions are systematically discussed.The related research on borylation reaction and arylcarbonitrile carbon cyanide bond borylation reaction,the research results obtained are as follows:1.Carboxylic acid thiophenol ester ortho-carbon-hydrogen bond borylation without metal participation.With boron tribromide as boron source and catalyst,and pivaloyl group as guide group,carboxylic acid thiophenol ester undergoes ortho-selective carbon-hydrogen bond borylation reaction at room temperature,and boron ester compound is obtained after adding pinacol and base.The reaction conditions are simple and mild,and have good substrate applicability.This method provides an efficient and simple method for the functionalization of ortho-carbon-hydrogen bonds of thiophenolic compounds.2.Metal-free borylation of arylcarbonitrile carbon-cyanide bonds.Under the mediation of boron trifluoride ether,benzonitrile and pinacol biboronate can undergo carbon-cyanide borylation to obtain phenylboronic esters in low yields.After continuous optimization of the reaction system,the yield of the target product still needs to be improved.Preliminary substrate range exploration showed good substrate suitability for this reaction.