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。
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.