Base-promoted Borylation Of Carbon-carbon Unsaturated Bonds With Bis(pinacolato) Diboron

Boron-containing compounds are important synthetic building blocks for carbon-carbon bond construction.Such functional groups exist in many drug molecules such as bortezomib.Therefore,how to construct boron-containing compounds with high selectivity has always been a research hotspot in organoboron chemistry.In the first work,i developed a selective borylation of carbon-carbon unsaturated bonds of propynols in ionic liquids.This method provides an efficient route to the construction of vinylboronates with high chemical selectivities.In the presence of B₂pin₂ as a boron source without the involvement of transition metals,inorganic bases such as K₂CO₃ can promote the borylation of carbon-carbon unsaturated bonds of electron-deficient alkynes or terminal alkynes,but the study of unreactive internal alkynes are relatively rare.I demonstrated that ionic liquids are superior mediums for the selective borylation of unreactive internal alkynes.The reaction was not oxygen sensitive and showed high chemical selectivies under mild conditions.It could be applied for late-stage derivation of some complex drug molecules.I successfully prepared a series of highly functionalized vinylboronateswith further derivatization.Moreover,if the amount of B₂pin₂ is increased,secondary borylation can be achieved affording a series of dehydroxylized vinylboronateswhich enriches the synthetic meaning of this method.Based on the work,I further developed a reductive aromatization of quinols with B₂pin₂as a deoxidizer.Quinol compounds with allyl alcohol structure are a type of building blocks containing hydroxyl,carbonyl and carbon-carbon double bonds.Since it is rich in reactive sites,it is an important constituent structure in various natural products and drug molecules,such as estrone or estradiol in steroids.In organic transformations of these structures,it is of challenge to achieve high selectivties with multiple reactive sitesTherefore,the synthetic method i developed provides an efficient route for the synthesis of phenolic drug intermediates which meanwhile lighten further developments in corresponding synthetic methodologies.