Oxidation products of fused 2-hetarylimidazole derivatives
摘要:
Oxidation of 5-(1-methyl-1H-benzimidazol-2-yl)thiophene-, and -selenophene-2-carbaldehydes with potassium dichromate in 20% aqueous sulfuric acid afforded the corresponding carboxylic acids. Analogous reaction with 5-(1-methyl-1H-benzimidazol-2-yl)furan-2-carbaldehyde led to the formation of 1-methyl-1H-benzimidazole as a result of decarboxylation of the primary oxidation product and subsequent decomposition of the furan ring. Probable factors responsible for instability of 5-(1H-benzimidazol-2-yl)-hetarene-2-carboxylic acids were considered. The oxidation of 2-furylnaphtho[2,3-d]- and 2-hetarylphenanthro-[9,10-d]imidazoles gave, respectively, an anthraquinone analog and 6,7-quinones. pi-Electron-rich heterocycles in 2-furyl- and 2-pyrrolylphenanthro[9,10-d]imidazoles were oxidized completely, being replaced by hydrogen.
Design and Syntheses of Palladium Complexes of NNN/CNN Pincer Ligands: Catalyst for Cross Dehydrogenative Coupling Reaction of Heteroarenes
作者:Vikki N. Shinde、Nattamai Bhuvanesh、Anil Kumar、Hemant Joshi
DOI:10.1021/acs.organomet.9b00695
日期:2020.1.27
of palladium(II) pincer complexes having NNN and CNN coordinationmodes. The new complexes were fully characterized with the help of 1H and 13C1H} NMR, HRMS, and IR spectroscopy. The structure and bonding modes of complexes were further authenticated with the help of single-crystal X-ray diffraction. Thermally robust and moisture-/air-insensitive palladium pincer complexes C1–C4 have been used as
该报告描述了具有NNN和CNN配位模式的新型钯(II)钳形配合物的简单合成。借助1 H和13 C 1 H} NMR,HRMS和IR光谱对新配合物进行了全面表征。借助单晶X射线衍射进一步验证了配合物的结构和键合模式。具有热稳定性且对湿气/空气不敏感的钯夹钳复合物C1 - C4已被用作两个杂芳烃的交叉脱氢偶联(CDC)反应的催化剂,发现非常有效。该催化剂仅用1.0 mol%的催化剂即可成功活化包括苯并咪唑,咪唑,苯并噻唑,咪唑并吡啶,噻吩和呋喃在内的多种杂芳烃的C–H键,仅偶联剂的收率就很高。该催化剂对CHO,COMe,COOMe,COOEt,CONHPh,Me,CN,Br和Cl等官能团具有极好的耐受性。此外,该催化剂可重复使用多达四个反应周期,而效率仅有很小的损失。通过控制实验研究了CDC反应的机理,已表明NNN钳形配体(C5)的乙酸钯类似物是活性催化剂。
Halo-Bridged Abnormal NHC Palladium(II) Dimer for Catalytic Dehydrogenative Cross-Coupling Reactions of Heteroarenes
作者:Sreejyothi P、Samaresh Chandra Sau、Pavan K. Vardhanapu、Swadhin K. Mandal
DOI:10.1021/acs.joc.8b01053
日期:2018.8.17
This work describes the dehydrogenative coupling of heteroarenes using a dimeric halo-bridged palladium(II) catalyst bearing an abnormal NHC (aNHC) backbone. The catalyst can successfully activate the C–Hbond of a wide range of heteroarenes, which include benzothiazole, benzoxazole, thiophene, furan, and N-methylbenzimidazole. Further, it exhibited good activity for heteroarenes bearing various functional
Palladium(II)-Catalyzed Oxidative C−H/C−H Cross-Coupling of Heteroarenes
作者:Peihua Xi、Fan Yang、Song Qin、Dongbing Zhao、Jingbo Lan、Ge Gao、Changwei Hu、Jingsong You
DOI:10.1021/ja909807f
日期:2010.2.17
of unsymmetrical biheteroaryl molecules has been developed via Pd(II)-catalyzed oxidative C-H/C-H cross-coupling of heteroarenes. An inversion in reactivity and selectivity has been achieved successfully to perform the desired heterocoupling. This process allows the heterocoupling of not only electron-rich N-containing heteroarenes (e.g., xanthines, azoles, and indolizines) but also electron-poor pyridine
已经通过 Pd(II) 催化的杂芳烃氧化 CH/CH 交叉偶联开发了一种合成不对称二杂芳基分子的有效方法。已成功实现反应性和选择性的反转以进行所需的异源偶联。该过程不仅允许富电子的含氮杂芳烃(例如黄嘌呤、唑类和吲哚嗪)杂偶联,而且允许贫电子的吡啶 N 氧化物与各种噻吩或呋喃杂偶联。
Synthesis of novel fluorescent 2,5-di(benzimidazol-2-yl) derivatives of furan, thiophene, selenophene, and 2,4-di(benzimidazol-2-yl)pyrrole
作者:M. M. El’chaninov、A. A. Aleksandrov
DOI:10.1134/s107036321605039x
日期:2016.5
thienylbenzazoles has shown that 2,5-di(benzimidazol-2-yl)derivatives of five-membered heterocycles with one heteroatom are promising from the viewpoint of requirements to fluorescent dyes and biological fluorescent probes. In the present work, we synthesized the 2,5-dibenzimidazolyl derivatives of furan, thiophene, selenophene and pyrrole.