6688-61-5Relevant articles and documents
Photoinduced Double Proton Tautomerism in 4-Azabenzimidazole
Chou, Pi-Tai,Wu, Guo-Ray,Wei, Ching-Yen,Cheng, Chung-Chih,Chang, Chen-Pin,Hung, Fa-Tsai
, p. 10042 - 10052 (1999)
The proton-transfer tautomerism of 4-azabenzimidazole (4ABI) mediated by hydrogen bonding formation has been studied in the ground as well as in the excited state by means of absorption and emission spectroscopies. Thermodynamics of self-association and hydrogen-bonded complexes in nonpolar solvents were obtained. Proton-transfer isomers of 4ABI have been determined by syntheses and spectral characterization of various 4ABI methyl derivatives. The 4ABI dimer and 1:1 4ABI/acetic acid complex possessing cyclic dual hydrogen bonds undergoes a fast excited-state double proton-transfer reaction, resulting in a proton-transfer tautomer emission. Surprisingly, however, the ESDPT is prohibited in the 4ABI/2-azacyclohexanone cyclic hydrogen-bonded complex. The results render the conclusion that photoinduced double proton transfer in the 4ABI hydrogen-bonded complex can be fine-tuned by its associated guest molecule, as further supported by the molecular modeling as well as ab initio calculations.
Cu-Catalyzed C-H Allylation of Benzimidazoles with Allenes
Dong, Yaxi,Breit, Bernhard
, p. 6765 - 6769 (2021/09/11)
CuH-catalyzed intramolecular cyclization and intermolecular allylation of benzimidazoles with allenes have been described. The reaction proceeded smoothly with the catalytic system of Cu(OAc)2/Xantphos and catalytic amount of (MeO)2MeSiH. This protocol features mild reaction conditions and a good tolerance of substrates bearing electron-withdrawing, electron-donating, or electron-neutral groups. A new catalytic mechanism was proposed for this copper hydride catalytic system.
The Chameleonic Nature of Platinum(II) Imidazopyridine Complexes
Pinter, Piermaria,Pittkowski, Rebecca,Soellner, Johannes,Strassner, Thomas
, p. 14173 - 14176 (2017/10/07)
The synthesis and characterization of cyclometalated C^C* platinum(II) complexes with unique photophysical properties, aggregation induced enhancement of the quantum yields with a simultaneous decrease of phosphorescence lifetimes, is reported. Additional
C2-Selective Branched Alkylation of Benzimidazoles by Rhodium(I)-Catalyzed C-H Activation
Tran, Ga?l,Confair, Danielle,Hesp, Kevin D.,Mascitti, Vincent,Ellman, Jonathan A.
, p. 9243 - 9252 (2017/09/11)
Herein, we report a Rh(I)/bisphosphine/K3PO4 catalytic system allowing for the first time the selective branched C-H alkylation of benzimidazoles with Michael acceptors. Branched alkylation with N,N-dimethyl acrylamide was successfully applied to the alkylation of a broad range of benzimidazoles incorporating a variety of N-substituents and with both electron-rich and -poor functionality displayed at different sites of the arene. Moreover, the introduction of a quaternary carbon was achieved by alkylation with ethyl methacrylate. The method was also shown to be applicable to the C2-selective branched alkylation of azabenzimidazoles.
Palladium-Catalyzed Suzuki Cross-Coupling of 2-Halo-Deazapurines with Potassium Organotrifluoroborate Salts in the Regioselective Synthesis of Imidazo[4,5-b]pyridine Analogues
Savitha, Bhaskaran,Sajith, Ayyiliath. M.,Joy, M. Nibin,Khader, K.K. Abdul,Muralidharan,Padusha, M. Syed Ali,Bodke, Yadav D.
, p. 618 - 630 (2016/07/06)
In this paper, we report the use of potassium organotrifluoroborate salts as nucleophilic organoboron reagents in the Suzuki cross-coupling reactions of 2-halo deazapurines. Regio-isomeric C-2-substituted imidazo[4,5-b]pyridine analogues were synthesized by employing this protocol in good to excellent yields. Whereas aryl and heteroaryl trifluoroborates reacted readily to give the coupled products in high yields, alkyltrifluoroborates were found to be less reactive. The utilization of tetrabutylammonium acetate was found to play a substantial role in enhancing the reaction rates of the cross-coupling process. Also, a comparative study was performed between boronic acids and potassium organotrifluoroborate salts.
N-Substituted Formamides as C1-Sources for the Synthesis of Benzimidazole and Benzothiazole Derivatives by Using Zinc Catalysts
Nale, Deepak B.,Bhanage, Bhalchandra M.
, p. 2835 - 2842 (2015/12/18)
An efficient and convenient one-pot protocol has been developed for the synthesis of a variety of benzimidazole, benzoxazole, and benzothiazole derivatives. This novel approach uses various o-phenylenediamines and N-substituted formamides (C1 sources) in a zinc-catalyzed cyclization in the presence of poly(methylhydrosiloxane) to afford the corresponding derivatives as sole products in moderate to excellent yields.
Regioselective C2-arylation of imidazo[4,5-b]pyridines
Macdonald, Jonathan,Oldfield, Victoria,Bavetsias, Vassilios,Blagg, Julian
, p. 2335 - 2347 (2013/04/23)
We show that N3-MEM-protected imidazo[4,5-b]pyridines undergo efficient C2-functionalisation via direct C-H arylation. Twenty-two substituted imidazo[4,5-b]pyridines are prepared and iterative, selective elaboration of functionalised imidazo[4,5-b]pyridin
S-3578, A new broad spectrum parenteral cephalosporin exhibiting potent activity against both methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa synthesis and structure-activity relationships
Yoshizawa, Hidenori,Itani, Hikaru,Ishikura, Koji,Irie, Tadashi,Yokoo, Katsuki,Kubota, Tadatoshi,Minami, Kyoji,Iwaki, Tsutomu,Miwa, Hideaki,Nishitani, Yasuhiro
, p. 975 - 992 (2007/10/03)
A series of 7-aminothiadiazolylcephalosporins having a 1-(substituted)-1H-imidazo[4,5-b]pyridinium group at the C-3′ position of the cephem nucleus were synthesized and evaluated for in vitro antibacterial activities. Among the cephalosporins prepared in
