Copper(II)-Catalyzed C–H Nitrogenation/Annulation Cascade of Ketene <i>N</i>,<i>S</i>-Acetals with Aryldiazonium Salts: A Direct Access to <i>N</i><sup>2</sup>-Substituted Triazole and Triazine Derivatives
Direct synthesis of N2-substituted triazole and triazine derivatives has been a challenge in N-heterocyclic chemistry. Under copper(II) catalysis ketene N,S-acetals, that is, alkylthio-substituted enaminones, efficiently reacted with aryldiazonium salts to allow the regioselective generation of functionally diverse N2-substituted 1,2,3-triazoles and 2,3-dihydro-1,2,4-triazines. The oxidant and base-dependent
N 2-取代的三唑和三嗪衍生物的直接合成一直是N-杂环化学中的挑战。在铜(II)催化下,烯酮N,S-乙缩醛(即烷硫基取代的烯胺酮)与芳基重氮盐有效反应,从而可以选择性选择性地生成功能多样的N2-取代的1,2,3-三唑和2,3-二氢键-1,2,4-三嗪。氧化剂和碱依赖性反应分别产生五元和六元的N-杂环产物。合成方案具有宽泛的底物范围,在温和条件下具有良好的官能团耐受性。机理研究表明,反应是通过烯基偶氮/亚氨基中间体进行的。
ZnCl
<sub>2</sub>
‐Catalyzed [4+1] Annulation of Alkylthio‐Substituted Enaminones and Enaminothiones with Sulfur Ylides
作者:Yuan He、Jiang Lou、Zhengkun Yu、Yong‐Gui Zhou
DOI:10.1002/chem.201905483
日期:2020.4.16
in the synthesis of potentially bioactive compounds and functional materials. Herein, we report an efficient Lewis acid ZnCl 2 -catalyzed [4+1] annulation of alkylthio-substituted enami-nones, that is, α -oxo ketene N,S -acetals, with sulfur ylides, affording 2-acyl-3-aminofuran derivatives. In a similar fashion, [4+1] annulation of the corresponding enaminothiones, that is, α -thioxo ketene N,S -acetals
A transition-metal-free olefinicC−Hazidoalkylthiolation protocol was developed through C(sp3)−Sbondcleavage of vinylsulfoniumsalts with sodium azide in air under aqueous conditions. An interrupted Pummerer/nucleophilc azidoalkylation cascade was developed for such a process. The practicability of the synthetic protocol was demonstrated by scale-up preparation of the azidoalkylthiolated tetrasubstituted
enaminones was achieved to access naphtho[1,8-bc]pyrans by oxidative annulation to internal alkynes. 1-Naphthols might be formed as the only products, depending on the steric and/or electronic environment around the aroyl moiety of the aryl enaminones or the electronic impact from the alkynes. With propargyl alcohols as the masked terminal alkynes, aryl enaminones underwent rhodium(III)- or rhodium(I)-catalyzed
铑 (III) 催化的芳基烯胺酮的三 C-H 键活化通过氧化环化成内部炔烃来获得萘并[1,8- bc ]吡喃。1-萘酚可能作为唯一的产物形成,这取决于芳基烯胺酮的芳酰基部分周围的空间和/或电子环境或来自炔烃的电子影响。使用炔丙醇作为掩蔽的末端炔烃,芳基烯胺酮经历铑 (III) 或铑 (I) 催化的内部烯基 C-H 键活化以提供官能化的丁-2-烯-1,4-二酮。所得萘并[1,8- bc ]吡喃具有高荧光,可通过氯化、溴化和二氟甲基化进一步转化,证明了合成方案的潜在实用性。