136343-75-4Relevant articles and documents
Hypervalent iodine(iii) catalyzed oxidative C-N bond formation in water: Synthesis of benzimidazole-fused heterocycles
Rao, D. Nageswar,Rasheed,Vishwakarma, Ram A.,Das, Parthasarathi
, p. 25600 - 25604 (2014)
An iodine(iii) catalyzed C(sp2)-H functionalization- intramolecular amination reaction of N-aryl-2-amino-N-heterocycles has been developed in water and under ambient conditions. This metal-free open-flask chemistry is general and successfully applied in synthesizing the benzimidazole-fused heterocycles pyrido[1,2-a]benzimidazole, benzimidazo[1,2-a]quinoline and benzimidazo[2,1-a]isoquinoline derivatives. the Partner Organisations 2014.
Palladium-Catalyzed Electro-oxidative C-H Amination toward the Synthesis of Pyrido[1,2- A[benzimidazoles with Hydrogen Evolution
Duan, Zhengli,Lei, Aiwen,Lu, Lijun,Shi, Renyi,Zeng, Li,Zhang, Lin,Zhang, Wenxin
, p. 3828 - 3831 (2020)
Transition-metal-catalyzed oxidative C-H/N-H coupling reaction is an important method to construct C-N bonds. However, stoichiometric oxidants were usually necessary. Here, we report a palladium-catalyzed electro-oxidative intramolecular C-H/N-H annulation reaction without an external oxidant or additive. A variety of pyrido[1,2-a]benzimidazoles were constructed by a simple, green, and mild path. Experimental results suggested that Pd(0) could be oxidized on the anode to be recycled.
Tunable Electrochemical C?N versus N?N Bond Formation of Nitrogen-Centered Radicals Enabled by Dehydrogenative Dearomatization: Biological Applications
Chen, Jianbin,Cui, Yuezhi,Gao, Wei,Han, Xiaoxin,Hu, Wei,Lv, Shide,Ma, Li,Niu, Liwei,Wang, Jian-Yong,Wu, Yanwei,Zhou, Jianhua,Zhou, Mingyang
supporting information, p. 11583 - 11590 (2020/05/06)
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?N bond formation reaction. Hence, pyrido[1,2-a]benzimidazole and tetraarylhydrazine frameworks were prepared through a sustainable transition-metal- and exogenous oxidant-free strategy with broad generality. Bioactivity assays demonstrated that pyrido[1,2-a]benzimidazoles displayed antimicrobial activity and cytotoxicity against human cancer cells. Compound 21 exhibited good photochemical properties with a large Stokes shift (approximately 130 nm) and was successfully applied to subcellular imaging. A preliminary mechanism investigation and density functional theory (DFT) calculations revealed the possible reaction pathway.
C-H cycloamination of N-aryl-2-aminopyridines and N-arylamidines catalyzed by an in situ generated hypervalent iodine(iii) reagent
He, Yimiao,Huang, Jinbo,Liang, Dongdong,Liu, Lanying,Zhu, Qiang
supporting information, p. 7352 - 7354 (2013/09/23)
A metal-free synthesis of 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 hypervalent iodine(iii) species generated in situ from iodobenzene (catalytic) and peracetic acid (stoichiometric). The reaction proceeded smoothly at ambient temperature to provide the corresponding N-heterocycles in good to excellent yields.
A metal-free tandem demethylenation/C(sp2)-H cycloamination process of N -Benzyl-2-aminopyridines via C-C and C-N bond cleavage
Liang, Dongdong,He, Yimiao,Liu, Lanying,Zhu, Qiang
, p. 3476 - 3479 (2013/07/26)
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.
On the importance of an acid additive in the synthesis of pyrido[1,2-a]benzimidazoles by direct copper-catalyzed amination
Masters, Kye-Simeon,Rauws, Tom R. M.,Yadav, Ashok K.,Herrebout, Wouter A.,Van Der Veken, Benjamin,Maes, Bert U. W.
supporting information; experimental part, p. 6315 - 6320 (2011/07/31)
Not just an acid! An expedient and highly modular synthesis of 6-, 7-, and 8-substituted pyrido[1,2-a]benzimidazoles (4) has been developed by a direct intramolecular C-H amination of N-phenylpyridin-2-amines (3). Efficient C-H 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. C-Cl aminations in N-(2-chloroaryl)pyridin-2-amines allow access to 9-substituted pyrido[1,2-a]benzimidazoles. Copyright
Synthesis of pyrido[1,2-a]benzimidazoles through a copper-catalyzed cascade C-N coupling process
Wu, Zhiqing,Huang, Qing,Zhou, Xiangge,Yu, Lintao,Li, Zhengkai,Wu, Di
supporting information; experimental part, p. 5242 - 5245 (2011/11/13)
A simple and efficient method for the preparation ofpyrido[1,2-a] benzimidazoles by a copper-catalyzed inter-and intramolecular C-N coupling cascade process was designed and carried out, and the products were obtained in moderate to excellent yields (up to 93 %).
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-a ]benzimidazoles from N-aryl-2-aminopyridines
Wang, Honggen,Wang, Yong,Peng, Changlan,Zhang, Jiancun,Zhu, Qiang
supporting information; experimental part, p. 13217 - 13219 (2010/11/04)
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
Heteroatomic photocyclization of fluorinated anilinoazines
Frolov
, p. 1047 - 1051 (2007/10/03)
New tetrafluoro derivatives of pyrido[1,2-a]benzimidazole and 1,3-dimethylpyrimido[1,2-a]benzimidazole were obtained as a result of photoinduced cyclization of 2-(pentafluoroanilino)pyridine and 4,6-dimethyl-2-(pentafluoroanilino)pyrimidine at the heterocyclic nitrogen atom. The cyclization quantum yield increases with increasing fluorine substitution of the benzene ring in the initial amine. 9,10-Anthraquinone-2,6-disulfonic acid sensitizes photocyclization of 2-(2,4-difluoroanilino)pyridine. Radical cations are presumed to participate in the reaction. 1998 MAHK Hayka/Interperiodica Publishing.
PHOTOCYCLIZATION OF HETEROARENES
Baklanov, M. V.,Frolov, A. N.
, p. 550 - 559 (2007/10/02)
The new reaction of the photocyclization of heteroarenes is described.It leads to the formation of condensed imidazoles with various structures.The relation of the acid-base properties to the course of the alkylation reaction was studied.For the case of 8-chlorodipyridoimidazole it was shown that mono- and diprotonation goes at the atom N5, but methylation at the atoms N5 and N6.
