Research On Peroxides Mediated Functionalization Of Arylboronic Acids And Oxidation Of Alcohols

In this research,diverse cyclic and acyclic peroxides were used as active reagents to explore two kinds of organic reactions,which are the functionalization of arylboronic acids and the oxidation of alcohols.In the first part,the in situ functionalization of arylboronic acids was developed,including hydroxylation and iododeboronation of arylboronic acids.In the second part,the combinations of cyclic peroxides as oxidants and different organic catalysts were explored in the oxidation of alcohol,and the reactivity and selectivity of corresponding reactive intermediates were probed.In the in situ hydroxylation of arylboronic acids,the hydroxylation was conducted under blue LED irradiation with oxygen,when tert-butyl hydroperoxide(TBHP)was the oxidant and trichloroacetonitrile was the additive.After screening the reaction conditions,the optimal reaction conditions were determined.Different substituted arylboronic acids were explored in this reaction conditions,and a wide range of functional groups were tolerant and late-stage functionalization were successful as well.Mechanistic studies showed that arylboronic acid as a Lewis acid and the trichloroacetimidates intermediate as a Lewis base formed a highly unstable Lewis adduct.Through density functional theory(DFT)calculation,light on/light off experiment,and ultraviolet visible absorption spectrum experiment,the mechanism of in situ hydroxylation was discussed,a multi of pathway mechanism was suggested.In the iododeboronation of arylboronic acids,malonoylperoxides(MPO)as the oxidant and tetrabutylammonium iodide(TBAI)as iodine source efficiently produce the corresponding iodinated aromatic compounds at room temperature.In the oxidation of alcohols,based on our previous research about peroxides and halides,the combination of cyclic diacyl peroxide and inorganic halides showed excellent reactivity in the oxidation of alcohols,which broke through the limitation of stoichiometric halide salt and realized the catalytic cycle.The combination of malonyl peroxide and tetrabutyl ammonium bromide(TBAB)effectively realized the oxidization secondary alcohols to corresponding ketones,and primary alcohols were also examined under this conditions.After the optimization of reaction conditions,TBAB was successfully reduced to the catalytic amount.A wide of functional groups and late-stage functionalization were successfully achieved in the following substrate scope studies.Through radical inhibition experiment and kinetic isotope effect(KIE)experiment,the reaction mechanism was explored.In the exploration of phthaloylperoxides(PPO)and 2-iodobenzoic acid system in the oxidation of alcohols,the optimal reaction condition was obtained,different substituted alcohols were smoothly oxidized to the corresponding ketones in good yields.The above mentioned mild reaction conditions are all metal-free and base-free,and can be conducted under simple operation.