4-dimethylaminopyridine-boryl Radical Promoted Regioselective Radical Hydroboration Of Electron-Deficient Alkenes

Organoboron compounds are extensively applied in the organic synthetic chemistry,drugs discovery and material science owing to its specific physical and chemical properties.Hence,various efficient approaches have been developed for the construction of diverse organoboron compounds.Over the past few years,the methods to access multi-substituted organoboron compounds,especially for ?-borylcarbonyl compounds,have attracted extensive attention due to the rich chemistries of both boron substituents and carbonyl groups.Based on our group previous work,a straightforwardmethod for the construction of ?-borylcarbonyl compounds was developed by the radical hydroboration of readily available ?,?-carbonyl compounds with the use of p-dimethylamiopyridine-borane as the boryl radical precursor.In addition,radical hydroboration reactions of other electron-poor alkenes have been also achieved.Futher derivatizations of borylated products were achieved,leading to various useful organic building blocks.The first chapter of this dissertation summarized the known approaches to access?-boron carbonyl compounds and their synthetic applications.The methods to construct unstable ?-borylcarbonyl compounds mainly include:alkyl boron compounds enabled 1,2-alkyl migration reactions;hydroboration reactions of ?,?-unsaturated carbonyl compounds;acylation reaction of ?-boron carbanion;rearrangement reaction of allyl alcohol compounds.The approaches to assemble stable ?-borylcarbonyl compounds include:hydroboration reactions;B-N and B-H insertion reactions of carbine intermediate;Lewis acid enabled 1,2-boron migration reactions;oxidation of alkenylboronates.The second chapter of this dissertation introduced a p-dimethylamiopyridine-boryl radical enabled radical hydroboration reactions of electron-deficient alkenes.In this work,the boryl radical underwent regioselective ?-addition to various ?,?-carbonyl compounds,affording valuable ?-borylcarbonyl compounds.This reaction features mild reaction conditions,remarkble regioselectivity,easy operation,broad substrate scope and functional group tolerance.In addition,radical hydroboration reactions of other electron-poor unsaturated alkenes have been achieved.Various useful organic building blocks could be accessed through diverse derivatizations of the resulting ?-borylcarbonyl compounds.