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。
On the Importance of an Acid Additive in the Synthesis of Pyrido[1,2‐
<i>a</i>
]benzimidazoles by Direct Copper‐Catalyzed Amination
作者:Kye‐Simeon Masters、Tom R. M. Rauws、Ashok K. Yadav、Wouter A. Herrebout、Benjamin Van der Veken、Bert U. W. Maes
DOI:10.1002/chem.201100574
日期:2011.5.27
8‐substituted pyrido[1,2‐a]benzimidazoles (4) has been developed by a direct intramolecular CH amination of N‐phenylpyridin‐2‐amines (3). Efficient CH amination of 3 could only be achieved in the presence of catalytic copper and an acid additive. The type of acid (pKa) proved to be crucial for the catalysis. CCl aminations in N‐(2‐chloroaryl)pyridin‐2‐amines allow access to 9‐substituted pyrido[1,2‐a]benzimidazoles
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
Copper-Catalyzed One-Pot Synthesis of Substituted Benzimidazo[1,2-a]quinolines
作者:Hong-Wei Jin、Bing-Wei Zhou、Jian-Rong Gao、Dong Jiang、Jian-Hong Jia、Zhen-Ping Yang
DOI:10.1055/s-0030-1258146
日期:2010.8
A one-pot procedure for the synthesis of substituted benzimidazo[1,2-a]quinolines from the corresponding benzimidazoles and 2-bromobenzaldehydes has been developed. The titled products were prepared through Knoevenagel condensation and copper-catalyzed intramolecular Ullmann-type coupling in moderate to good yields. Knoevenagel condensation - copper catalyst - Ullmann coupling - quinoline synthesis
已经开发了从相应的苯并咪唑和2-溴苯甲醛合成一取代苯并咪唑并[1,2- a ]喹啉的一锅法。通过Knoevenagel缩合和铜催化的分子内Ullmann型偶联制备标题产物,产率中等至良好。 Knoevenagel缩合-铜催化剂-Ullmann偶联-喹啉合成-级联工艺