Copper and cobalt co-catalyzed aerobic oxidative cross-dehydrogenative coupling reaction of (benzo)azoles
作者:Yanrong Li、Fen Qian、Xia Ge、Tao Liu、Hitesh B. Jalani、Hongjian Lu、Guigen Li
DOI:10.1039/c9gc02464f
日期:——
The dehydrogenativecross-coupling (CDC) reaction of diversely substituted azoles, synergistically catalyzed by copper and cobalt, is reported. This protocol represents the first example of the use of air as an oxidant to carry out this chemical reaction. The process provides a convenient and economical method for the construction of valuable unsymmetrical bis-heteroaryl compounds, including bis-benzoazole
PdCl(dppb)(C3H5) as a catalyst, a range of heteroaryl derivatives undergoes coupling via C–Hbondactivation/functionalization reaction with chloropyridines or chloroquinolines in low to high yields. This air-stable catalyst can be used with a wide variety of substrates. The position of the chloro substituent on pyridines has a minor influence on the yields. On the other hand, the nature on the heteroaryl derivative
芳基氯化物与杂芳烃的直接偶联将具有可持续发展的巨大优势,因为它们的成本更低,质量更轻,可用化合物的多样性更大,并且还因为仅形成了与副产物碱有关的HCl和减少制备这些化合物的步骤数。我们观察到通过使用PdCl(dppb)(C 3 H 5)作为催化剂,一系列杂芳基衍生物通过C–H键活化/官能化反应与氯吡啶或氯喹啉进行低至高收率的偶联。这种空气稳定的催化剂可与多种基材一起使用。吡啶上氯取代基的位置对收率影响很小。另一方面,杂芳基衍生物的性质具有很大的影响。使用苯并恶唑,噻吩或噻唑衍生物可获得最高的收率。氯吡啶与呋喃的偶联也得到了预期的产物,但是产率低至中等。
Synthesis of benzoxazoles, benzothiazoles and benzimidazoles and evaluation of their antifungal, insecticidal and herbicidal activities.
Benzoxazoles, benzothiazoles and benzimidazoles having substituents on the azole and benzene nuclei were synthesized evaluated for antifungal, insecticidal and herbicidal activities. It was found that benzimidazoles tended to exhibit antifungal activity while benzothiazoles tended to show herbicidal activity. Chloro, trifluoromethyl, methoxy and ethoxy groups at the 5 position were potent substituents, and the 2-pyridyl group at the 2 position is a common structural unit. Among several active derivatives, 7-chloro-2-(2-pyridyl) benzimidazole and 2-(2-pyridyl)-5-trifluoromethylbenzothiazole exhibited significant activity against Panonycus citri.
Oxidative NHC catalysis for base-free synthesis of benzoxazinones and benzoazoles by thermal activated NHCs precursor ionic liquid catalyst using air as oxidant
作者:Youkang Zhou、Wei Liu、Yuchen Liu、Jiali Guan、Jieying Yan、Jian-Jun Yuan、Duan-Jian Tao、Zhibin Song
DOI:10.1016/j.mcat.2020.111013
日期:2020.8
A reusable thermal activated NHC precursor ionic liquid catalyst ([BMIm](2)[WO4]) has been prepared and developed for the synthesis of nitrogen-containing heterocycles such as benzoxazinones and benzoazoles through imines activation. [BMIm](2)[WO4] exhibited the good activity for the base-free condensation and oxidative NHC catalysis tandem under air atmosphere. The catalyst can be recovered and reused for at least five runs in gram scale synthesis without any decrease in catalytic activity. Furthermore, the control experiments demonstrated that the reaction involved formation of aromatic aldimines, NHC-catalyzed oxidative formation of imidoyl azoliums and intramolecular cyclization to generate the product.