Boryl Radical-Promoted Deoxygenative Alkylation Of Benzyl Acetates

Alcohols are abundant in nature and readily accessible in large quantities,which have been widely used as starting materials in synthetic chemistry.Radical deoxygenation is an efficient strategy for conversion of these readily accessible chemicals into value-added compounds,and it has unique advantages in compatibility and application scenarios in comparison with traditional nucleophilic or electrophilic reactions.According to whether the pre-or in-situ functionalization of alcohols with activating groups is required or not,radical deoxygenation can be divided into indirect deoxygenation and direct deoxygenation.Up to date,various protocols have been reported,most of these were limited to the use of precious metal catalysts,stoichiometric metal reducing agents,complex additives,harsh conditions,and specific substrates.Therefore,exploration of efficient deoxygenation methods with a wide range of substrates is needed.This thesis presents a boron radical-promoted deoxygenative alkylation reaction of benzyl acetates,which enabled efficient conversions of various primary,secondary,and tertiary benzyl alcohols under mild conditions.The first chapter summarizes the development of deoxygenative functionalizations of alcohols from two aspects:1)reactions required pre-or in-situ activation of alcohols are summarized as indirect deoxygenative functionalizations;2)functionalization of free alcohols are summarized as direct deoxygenative functionalizations.The second chapter,at first,introduced the development of boron radicals and our group’s research on the properties of Lewis base-boron radicals,including the construction of C-B bonds and the activation of C-X bonds are introduced.Based on the previous research,we designed and realized the deoxyalkylation of benzyl acetate promoted by Lewis base-boryl radical.The reaction starts from the attack of a 4-dimethylaminopyridine(DMAP)-boryl radical to the carbonyl oxygen atom,and then β-fragmentation to generates benzyl radical intermediate,which is captured by alkene to provide the target product.This strategy provides an efficient method for the deoxygenative functionalization of alcohols.It allows for the functionalization of various primary,secondary,and tertiary alcohols.A one-step gram reaction is also achieved.Benzyl alcohol is converted to acetate,which is directly used for deoxygenative alkylation without separation to obtain the target product with high yield.The third chapter is the experimental part,which introduces the instruments and reagents used in the experiment,the synthesis routes of substrates,and the characterization data of the products.