A Metal-Free Tandem Demethylenation/C(sp<sup>2</sup>)–H Cycloamination Process of <i>N</i>-Benzyl-2-aminopyridines via C–C and C–N Bond Cleavage
作者:Dongdong Liang、Yimiao He、Lanying Liu、Qiang Zhu
DOI:10.1021/ol4015656
日期:2013.7.5
A mild, metal-free synthesis of pyrido[1,2-a]benzimidazoles starting with N-benzyl-2-aminopyridines, which employs PhI(OPiv)2 as a stoichiometric oxidant, has been developed. The process is initiated by an unusual PhI(OPiv)2-mediated ipso SEAr reaction, followed by solvent-assisted C–C and C–N bond cleavage.
已经开发了一种轻度,无金属的合成方法,该方法以N-苄基-2-氨基吡啶为原料,以PhI(OPiv)2为化学计量氧化剂,合成了吡啶并[1,2- a ]苯并咪唑类化合物。该过程由一个不寻常的岛(OPiv)发起2介导的本位小号ë的Ar反应,接着进行溶剂辅助C-C和C-N键断裂。
Tunable Electrochemical C−N versus N−N Bond Formation of Nitrogen‐Centered Radicals Enabled by Dehydrogenative Dearomatization: Biological Applications
Herein, an environmentally friendly electrochemical approach is reported that takes advantage of the captodative effect and delocalization effect to generate nitrogen‐centered radicals (NCRs). By changing the reaction parameters of the electrode material and feedstock solubility, dearomatization enabled a selective dehydrogenative C−N versus N−Nbondformation reaction. Hence, pyrido[1,2‐a ]benzimidazole
本文报道了一种环境友好的电化学方法,该方法利用俘获作用和离域作用产生氮中心自由基(NCR)。通过改变电极材料的反应参数和原料溶解度,脱芳香化使选择性脱氢的CN与NN键形成反应成为可能。因此,吡啶[1,2- a ]苯并咪唑和四芳基肼构架是通过具有广泛普遍性的可持续的无过渡金属和外源氧化剂的策略制备的。生物活性测定表明,吡啶并[1,2- a ]苯并咪唑类化合物具有抗微生物活性和对人类癌细胞的细胞毒性。化合物21具有良好的光化学性质,具有大的斯托克斯位移(约130 nm),并成功应用于亚细胞成像。初步的机理研究和密度泛函理论(DFT)计算揭示了可能的反应途径。
A Direct Intramolecular C−H Amination Reaction Cocatalyzed by Copper(II) and Iron(III) as Part of an Efficient Route for the Synthesis of Pyrido[1,2-<i>a</i>]benzimidazoles from <i>N</i>-Aryl-2-aminopyridines
A novel and efficient synthesis of pyrido[1,2-a]benzimidazoles through direct intramolecular aromatic C-H amination of N-aryl-2-aminopyridines has been developed. The reaction, cocatalyzed by Cu(OAc)(2) and Fe(NO(3))(3)·9H(2)O, is carried out in DMF under a dioxygen atmosphere. Diversified pyrido[1,2-a]benzimidazoles containing various substitution patterns are obtained in moderate to excellent yields
diversified pyrido[1,2-a]benzimidazoles and 1H-benzo[d]imidazoles from N-aryl-2-aminopyridines and N-arylamidines has been developed. The C-H cycloamination reaction was catalyzed by hypervalentiodine(III) speciesgenerated in situ from iodobenzene (catalytic) and peracetic acid (stoichiometric). The reaction proceeded smoothly at ambient temperature to provide the corresponding N-heterocycles in good
2-a]benzimidazoles, which show interesting and potentially useful biological activities, have drawn extensive attention from chemists. A straightforward copper acetate-oxidative one-pot synthesis of these compounds from 2-aminopyridines and phenylboronic acids through C–Nbondformation and C–Hbondactivation was developed as a simple and convenient method.