Merging the ring opening of benzoxazoles with secondary amines and an iron-catalyzed oxidative cyclization towards the environmentally friendly synthesis of 2-aminobenzoxazoles
A Metal-Free Amination of Benzoxazoles – The First Example of an Iodide-Catalyzed Oxidative Amination of Heteroarenes
作者:Tanja Froehr、Christian P. Sindlinger、Ulrich Kloeckner、Peter Finkbeiner、Boris J. Nachtsheim
DOI:10.1021/ol201439t
日期:2011.7.15
An efficient transition-metal-free amination of benzoxazoles has been developed. With catalytic amounts of tetrabutylammoniumiodide (TBAI), aqueous solutions of H2O2 or TBHP as co-oxidant and undermild reaction conditions, highly desirable 2-aminobenzoxazoles were isolated in excellent yields of up to 93%. First mechanistic experiments indicate the in situ iodination of the secondary amine as the
已经开发出有效的无过渡金属苯并恶唑胺化的方法。用催化量的四丁基碘化铵(TBAI),H 2 O 2或TBHP水溶液作为助氧化剂,并在温和的反应条件下,以高达93%的优异收率分离出了非常理想的2-氨基苯并恶唑。最初的机械实验表明,仲胺的原位碘化是假定的活化方式。
Catalyst- and Reagent-Free Electrochemical Azole C−H Amination
作者:Youai Qiu、Julia Struwe、Tjark H. Meyer、João C. A. Oliveira、Lutz Ackermann
DOI:10.1002/chem.201802832
日期:2018.9.3
Catalyst‐ and chemical oxidant‐free electrochemical azole C−H aminations were accomplished via cross‐dehydrogenative C−H/N−H functionalization. The catalyst‐free electrochemical C−H amination proved feasible on azoles with high levels of efficacy and selectivity, avoiding the use of stoichiometric oxidants under ambient conditions. Likewise, the C(sp3)−H nitrogenation proved viable under otherwise
Going to the source: Formamides or parentamines were used as an aminogroupsource for the silver‐mediated amination of benzoxazoles. Although reactions with formamides proceeded at high temperatures, the directamination with amines took place under much milder conditions (see scheme). Optically active aminogroups could also be installed without racemization.
Heterogeneously Porous γ-MnO<sub>2</sub>-Catalyzed Direct Oxidative Amination of Benzoxazole through CH Activation in the Presence of O<sub>2</sub>
作者:Provas Pal、Arnab Kanti Giri、Harshvardhan Singh、Subhash Chandra Ghosh、Asit Baran Panda
DOI:10.1002/asia.201402057
日期:2014.9
Oxidative amination of azoles through catalyticCHbond activation is a very important reaction due to the presence of 2‐aminoazoles in several biologically active compounds. However, most of the reported methods are performed under homogeneous reaction conditions using excess reagents and additives. Herein, we report the heterogeneous, porous γ‐MnO2‐catalyzed direct amination of benzoxazole with
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<i>n</i>
</sup>Bu<sub>4</sub>NI-catalyzed direct amination of benzoxazoles with tertiary amines using TBHP as oxidant under microwave irradiation
Abstract A facile, efficient, and practical method for nBu4NI-catalyzed direct C–H amination of benzoxazoles with tertiary amines has been developed. The system could be performed in the absence of metal catalyst and only requires tert-butyl hydroperoxide as oxidant under microwave irradiation. A variety of substituted benzoxazol-2-amines were synthesized with moderate to good yield.