Radical Hydroboration-Involved One-Pot Synthesis Of Boron-Handled Glycol Derivatives

As commonly used organic synthons,ethylene glycols and their derivatives have wide applications due to their unique physical and chemical properties.Fossil fuels and biomass derivatives were commonly used as precursors of ethylene glycols and their derivatives,such as ethylene oxide,glycerol,syngas(water gas)and saccharide,etc.Although biomass-based synthesis of ethylene glycols was one of the ideal methods,it still had major limitations for its further applications.Hydroboration of carbon-carbon unsaturated bonds was a powerful method to build boron-containing organic frameworks with high atomic efficiency.Along with the development of radical reactions,radical hydroboration,which could be performed under relatively mild conditions with broad functional group tolerance,has become an important tool for the synthesis of organoborons.This thesis introduced a unique synthetic method of boron-containing ethylene glycol derivatives in a one-pot fashion involving a radical hydroboration of ?,?-unsaturated acetals as the key step.The reaction mechanism has been confirmed by control experiment studies and a deuterium-labeling experiment.Chapter one briefly introduced the discovery and the development of traditional electrophilic hydroboration reactions and transition metal-catalyzed hydroboration reactions.After that,the formation and reactions of Lewis base-boryl radicals have been discussed with a focus on radical hydroboration reactions.Chapter two introduced a one-pot transformation for the assembly of boron-tethered ethylene glycol derivatives involving a radical hydroboration of?,?-unsaturated acetals as the key step.Based on our previous research on radical hydroboration of alkenes,a unique radical hydroboration of ?,?-unsaturated acetals has been established.Following this step,the treatment with hydrochloric acid and pinacol led to a series of boron-containing ethylene glycol derivatives.Based on the results of control experiments and a deuterium-labeling experiment,a plausible pathway of this transformation has been proposed.