Application Of Arylboronic Acids In Michael Addition Areaction And Esterification Of Aldehydes

Arylboronic acids reagents are frequently used by organic chemist because theyare thermally stable and functionally compatible as well as insensitive to air andmoisture. Therefore, researches dealing with the bond formation reaction ofarylboronic acids catalyzed by transitional metal have been extensively explored.Initially, this thesis has reviewed the development and application of arylboronicacids in the bond formation reactions related to C-C and C-X（hetero atom）, and thenthe work involved C-C and C-O formation reactions were carried out. Mainly, theexperiments consisted of two sections:1) Formation of C-C bond via1,4-addition ofarylboronic acids to α, β-unsaturated substrates using nickel complexes.Comparingwith palldium and rhodium-catalyzed Michael addition reactions, monovalentnickel-catalyzed process afforded products in morderate yields. Moreover, theexperiments have proved that dimine derived from aromatic aldehyde are prior to theorganic phosphorus ligand and afforded good yields, wherein negative effect ocurredin the presence of water or base in this catalytic system.Meanwhile, it was also foundthat when KI was employed as additive the self-coupling reaction of arylboronicacids was suppressed.Based on the EPR dates, the monovalent nickel catalyticprogress was tentatively proposed. In view of the reported Ni（II） and Ni（0）-catalyzedmechanisms previously examined, this Ni（I） catalytic progress has extendedmechanismic reseaches of the nickel catalytic Michael addition.2) Formation of C-O bond via N-heterocyclic carbene-catalyzed aerobic oxidativedirect esterification of aldehydes with arylboronic acids. Results indicated that seriesof aryl benzoate derivatives were produced at80℃in air. This process wasconducted without the metal catalyst. And it has been proved to be a simple andoperative reaction relative to traditional benzoin reaction and Baeyer-Villigeroxidative reaction. Additionally, both of the two substrates have shown goodfunctional compatibility. Further investigation revealed a mechanism involving anucleophilic substitution reaction between B（OR）₃and acyl azolium species,differing from the concerted mechanism proposed by Anand through controllingexperiments.Although the monovalent nickel catalyzed Michael addition reaction offered lowyields, it is expected that chang of ligand maybe favor the improvement of yields dueto the catalysts and ligands both responsible for high yields. On the other hand, in the N-heterocyclic carbene-catalyzed esterification reaction, aliphatic aldehydes orboronic acids possibly were employed after further exploration.