Copper-Catalyzed Oxidative Amination of Benzoxazoles via C−H and C−N Bond Activation: A New Strategy for Using Tertiary Amines as Nitrogen Group Sources
method for oxidative amination of azoles with tertiary aminesviacopper-catalyzed C−H and C−Nbond activation has been developed. This protocol can be performed in the absence of external base and only requires atmospheric oxygen as oxidant. The catalyst system is very simple and efficient, which opens a new way for using tertiary amines as nitrogen group sources for C−Nbondformation reactions.
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。
Amination of Benzoxazoles and 1,3,4-Oxadiazoles Using 2,2,6,6-Tetramethylpiperidine-N-oxoammonium Tetrafluoroborate as an Organic Oxidant
作者:Sebastian Wertz、Shintaro Kodama、Armido Studer
DOI:10.1002/anie.201104735
日期:2011.11.25
No transition metals are necessary to convert benzoxazoles and 1,3,4‐oxadiazoles into the corresponding pharmacologically interesting 2‐aminated heterocycles by formal direct C(2)‐aminationusing tetramethylpiperidine‐N‐oxoammonium tetrafluoroborate (TEMPO+BF4−) as an oxidant (see scheme; TEMP=2,2,6,6‐tetramethylpiperidine; TfOH=trifluoromethanesulfonic acid).
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.
Copper-Catalyzed Electrophilic Amination of Heteroarenes and Arenes by CH Zincation
作者:Stacey L. McDonald、Charles E. Hendrick、Qiu Wang
DOI:10.1002/anie.201311029
日期:2014.4.25
Direct amination of heteroarenes and arenes has been achieved in a one‐pot CH zincation/copper‐catalyzed electrophilic amination procedure. This amination method provides an efficient and rapid approach to access a diverse range of heteroaromatic and aromatic amines including those previously inaccessible using CH amination methods. The mild reaction conditions and good functional‐group compatibility
杂芳烃和芳烃的直接胺化已经在一锅C - H锌化/铜催化的亲电胺化过程中实现。这种胺化方法提供了一种高效、快速的方法来获得各种杂芳胺和芳香胺,包括以前使用 C - H 胺化方法无法获得的胺。温和的反应条件和良好的官能团相容性证明了其在合成重要且复杂的胺类方面的巨大潜力。