2620-82-8Relevant articles and documents
Preparation of 2-substituted benzimidazoles and related heterocycles directly from activated alcohols using TOP methodology
Wilfred, Cecilia D.,Taylor, Richard J. K.
, p. 1628 - 1630 (2004)
A one-pot procedure for preparing 2-substituted benzimidazoles directly from activated alcohols in good to excellent yields using a new Tandem Oxidation Process (TOP) is reported. The use of this methodology to prepare 2-substituted benzoxazoles and 2-substituted benzothiazoles is also described.
Bimetallic Cooperative Catalysis for Decarbonylative Heteroarylation of Carboxylic Acids via C-O/C-H Coupling
Liu, Chengwei,Ji, Chong-Lei,Zhou, Tongliang,Hong, Xin,Szostak, Michal
supporting information, p. 10690 - 10699 (2021/04/09)
Cooperative bimetallic catalysis is a fundamental approach in modern synthetic chemistry. We report bimetallic cooperative catalysis for the direct decarbonylative heteroarylation of ubiquitous carboxylic acids via acyl C-O/C-H coupling. This novel catalytic system exploits the cooperative action of a copper catalyst and a palladium catalyst in decarbonylation, which enables highly chemoselective synthesis of important heterobiaryl motifs through the coupling of carboxylic acids with heteroarenes in the absence of prefunctionalization or directing groups. This cooperative decarbonylative method uses common carboxylic acids and shows a remarkably broad substrate scope (>70 examples), including late-stage modification of pharmaceuticals and streamlined synthesis of bioactive agents. Extensive mechanistic and computational studies were conducted to gain insight into the mechanism of the reaction. The key step involves intersection of the two catalytic cycles via transmetallation of the copper–aryl species with the palladium(II) intermediate generated by oxidative addition/decarbonylation.
Ruthenium-Catalyzed ortho- And meta-H/D Exchange of Arenes
Zhao, Liang-Liang,Liu, Wei,Zhang, Zengyu,Zhao, Hongyan,Wang, Qi,Yan, Xiaoyu
, p. 10023 - 10027 (2019/12/24)
Ruthenium-catalyzed aromatic H/D exchange in [D4]acetic acid has been developed. By using N-heteroarenes as directing groups, both ortho and meta positions are selectively deuterated with high levels of D incorporation. Moreover, this strategy provides an alternative way to achieve meta-C-H activation.
An intramolecular C(sp3)-H imination using PhI-m CPBA
Bose, Anima,Maiti, Saikat,Sau, Sudip,Mal, Prasenjit
, p. 2066 - 2069 (2019/02/19)
Herein, a highly exothermic primary amine-polyvalent iodine reaction has been used successfully for selective functionalization of acidic C(sp3)-H groups for a dehydrogenative C-H imination reaction by 4H elimination. Overall, C(sp3)-H imination at 1,5 distances was readily done via organocatalysis using PhI (10 mol%)-mCPBA under ambient conditions.
Intramolecular C(sp3)–H Imination towards Benzimidazoles Using Tetrabutylammonium Iodide and tBuOOH
Bose, Anima,Sau, Sudip,Mal, Prasenjit
, p. 4105 - 4109 (2019/06/24)
Development of sustainable and economically viable methods is challenging but desired in organic synthesis. Herein, intramolecular C(sp3)–H imination between a free amine group and N-methylene group is established using TBAI (20 mol %)-TBHP (3.0 equiv.) in DMSO which is found to be an inexpensive replacement of PhI-mCPBA in HFIP.
Microwave assisted synthesis and potent antimicrobial activity of some novel 1,3-dialkyl-2-arylbenzimidazolium salts
Eren, Bilge,Yilmaz, ?zge,?etin, Gül?in,Darcan, Cihan
, p. 621 - 633 (2018/06/06)
Background: Benzimidazolium salts include biologically active benzimidazole ring. Some benzimidazolium salts and their metal complexes, containing different groups, showed remarkable antibacterial, antifungal and antitumor effects. Most of these studies are generally related with the 2-unsubstituted derivatives of benzimidazolium salts which named as N-heterocyclic carbenes (NHCs). To enhance the efficacy of the benzimidazoles in the biological systems, it is very important to overcome the insolubility problem. For this reason and previously indicated structural importance of the benzimidazolium salts, 1,3-dialkyl halide salts of the 2-arylbenzimidazoles, are of focus in this work. To the best of our knowledge, this is the first report that describes the microwave assisted synthesis and antimicrobial activity of 2-arylsubstituted benzimidazolium salts. Methods: A series of novel 1,3-dialkyl-2-arylbenzimidazolium salts (8-28) were synthesized via the N-alkylation of 1-methyl-2-arylbenzimidazole derivatives (1-7) with alkyl halides under microwave conditions by using small amount of DMF. The results were also compared with conventional heating under reflux. Structures of the products were confirmed by using 1H-NMR, 13C-NMR, FTIR spectroscopic techniques. All of the synthesized compounds were screened for their in vitro antimicrobial activities using microbroth tube dilution and disc diffusion methods. Results: Considering the reactions repeated by classical heating, it was determined that the reaction times were decreased from 3-6 hours to 5-35 minutes under microwave. Additionally, yields have increased from 4-71 % to 64-96 % ranges. Considering the whole antimicrobial activity studies, MIC values of newly synthesized benzimidazolium salts 8-28 (1.95->1500 μg/ml) are remarkably smaller than parent benzimidazoles 1-7 (62.5->1500 μg/ml) on the studied microorganisms. Conclusion: The microwave method is advantageous regarding the usage of mild conditions and small amounts of solvent, easy purification and achieving high yields in short times. The antimicrobial activity studies demonstrate that newly synthesized salts (8-28) are effective mostly on grampositives and eukaryotic microorganisms. Compounds 16, 18, 19, 24, 25 and 27 were found to be the most effective inhibitors of growth in both gram-positive bacteria and eukaryotes. Thus, the synthesized compounds in this study may aid the treatment of fungal and bacterial diseases. The results of this study are of great significance in the areas of synthetic organic chemistry, microbiology, pharmaceutical chemistry and chemical catalysis.
Synthesis of 1,2-disubstituted benzimidazoles using an aza-Wittig-equivalent process
Chen, Yuan,Xu, Fanghui,Sun, Zhihua
, p. 44421 - 44425 (2017/09/26)
A synthetic approach for 1,2-disubstituted benzimidazoles has been successfully designed based on effective C-N bond construction, which demonstrated mild reaction conditions and excellent yields. The method involves treating derivatives of o-phenylenediamine with tert-butanesulfoxide and NBS under acidic conditions, which undergoes an aza-Wittig-equivalent process to afford the desired products. Using this method, a series of benzimidazoles containing multiple functional groups with varying electronic effects have been successfully constructed.
Catalytic Oxidative Coupling of Primary Amines under Air: A Flexible Route to Benzimidazole Derivatives
Nguyen, Khac Minh Huy,Largeron, Martine
supporting information, p. 1025 - 1032 (2016/03/01)
Benzimidazoles are of fundamental importance in chemistry and biology, and the development of efficient, environmentally benign methods for their preparation remains a key challenge for organic chemists. In a biomimetic approach inspired by copper amine oxidases, we disclose herein the scope and factors influencing the success of the cooperative action of CuBr2 as electron-transfer mediator and a topaquinone-like substrate-selective catalyst in the oxidative cyclocondensation of primary amines with o-aminoanilines. This one-pot atom-economic multistep process, which works under green conditions with ambient air as the terminal oxidant, low loadings of catalyst, and equimolar amounts of commercially available amine substrates, is particularly suitable for the preparation of 1,2-disubstituted benzimidazoles. Furthermore, it allows the functionalization of nonactivated primary aliphatic amines, which are known to be challenging substrates for non-enzymatic catalytic aerobic systems.
C-H arylation and alkenylation of imidazoles by nickel catalysis: Solvent-accelerated imidazole C-H activation
Muto, Kei,Hatakeyama, Taito,Yamaguchi, Junichiro,Itami, Kenichiro
, p. 6792 - 6798 (2015/11/24)
The first nickel-catalyzed C-H arylations and alkenylations of imidazoles with phenol and enol derivatives are described. Under the influence of Ni(OTf)2/dcype/K3PO4 (dcype: 1,2-bis(dicyclohexylphosphino)ethane) in t-amyl alcohol, imidazoles can undergo C-H arylation with phenol derivatives. The C-H arylation of imidazoles with chloroarenes as well as that of thiazoles and oxazoles with phenol derivatives can also be achieved with this catalytic system. By changing the ligand to dcypt (3,4-bis(dicyclohexylphosphino)thiophene), enol derivatives could also be employed as coupling partners achieving the C-H alkenylation of imidazoles as well as thiazoles and oxazoles. Thus, a range of C2-arylated and alkenylated azoles can be synthesized using this newly developed nickel-based catalytic system. The key to the success of the C-H coupling of imidazoles is the use of a tertiary alcohol as solvent. This also allows the use of an air-stable nickel(ii) salt as the catalyst precursor.
Nanoparticle mediated organic synthesis (NAMO-synthesis): CuI-NP catalyzed ligand free amidation of aryl halides
Kumar, Atul,Bishnoi, Ajay Kumar
, p. 41631 - 41635 (2015/05/20)
The first CuI-nanoparticle catalyzed ligand free synthesis of N-aryl amides from aryl halides and arylamides/cyclic amides has been developed. This methodology is further extended for the synthesis of nitrogen heterocycles such as benzimidazole, and quinazolinone via intermolecular amidation reaction followed by cyclization. TEM images of the CuI-NP catalyst showed spherical, well-dispersed particles which provide large surface area for reactivity and have good recyclability. This journal is
