- A rapid method for the preparation of 2-substituted oxazolo[4,5-b]pyridines using microwave-assisted direct condensation reactions
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The condensation reaction of 2-amino-3-hydroxypyridine with different carboxylic acids by microwave-assisted heating is a fast method for producing libraries based on fused 2-substituted oxazolo[4,5-b]pyridines in moderate to good yields.
- Myllym?ki, Mikko J.,Koskinen, Ari M.P.
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- Tuning the Excited State of Tetradentate Pd(II) and Pt(II) Complexes through Benzannulated N-Heteroaromatic Ring and Central Metal
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A series of tetradentate Pd(II) and Pt(II) complexes containing fused 5/6/6 metallocycles with phenyl N-heteroaromatic benzo[d]imidazole (pbiz), benzo[d]oxazole (pboz) or benzo[d]thiazole (pbthz)-containing ligands was developed. Systematic studies by exp
- Fang, Xiaoli,Guo, Hua,Li, Guijie,Lou, Weiwei,She, Yuanbin,Sun, Yulu,Yang, Yun-Fang,Zhang, Qisheng
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p. 223 - 234
(2021/12/16)
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- 2-Aryl benzazole derived new class of anti-tubercular compounds: Endowed to eradicate mycobacterium tuberculosis in replicating and non-replicating forms
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The high mortality rate and the increasing prevalence of Mtb resistance are the major concerns for the Tuberculosis (TB) treatment in this century. To counteract the prevalence of Mtb resistance, we have synthesized 2-aryl benzazole based dual targeted molecules. Compound 9m and 9n were found to be equally active against replicating and non-replicating form of Mtb (MIC(MABA) 1.98 and 1.66 μg/ml; MIC(LORA) 2.06 and 1.59 μg/ml respectively). They arrested the cell division (replicating Mtb) by inhibiting the GTPase activity of FtsZ with IC50 values 45 and 64 μM respectively. They were also capable of kill Mtb in non-replicating form by inhibiting the biosynthesis of menaquinone which was substantiated by the MenG inhibition (IC50 = 11.62 and 7.49 μM respectively) followed by the Vit-K2 rescue study and ATP production assay.
- Datta, Dhrubajyoti,Debnath, Joy,Franzblau, Scott G.,Ghosh, Kalyan Sundar,Hari, Natarajan,Ma, Rui,Rana, Shiwani,Velappan, Anand Babu
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- Synthesis and characterization of a novel oxo-bridged binuclear iron(iii) complex: Its catalytic application in the synthesis of benzoxazoles using benzyl alcohol in water
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In the present work, the synthesis and characterization of a novel binuclear oxo-bridged iron(iii) complex, (FeLAPIP)2O, where LAPIP is the deprotonated form of a tetradentateo-aminophenol-iminopyridine ligand, is described. The iron complex was characterized using different techniques including X-ray crystallography, infrared spectroscopy, UV-Vis, magnetic susceptibility and cyclic voltammetry. The X-ray structure analysis revealed that in the structure of the (FeLAPIP)2O complex, each iron(iii) is coordinated in a distorted square pyramidal arrangement by an oxo group, three amine nitrogens and one oxygen atom of the o-aminophenolate ligand. The variable-temperature magnetic measurement exhibits strong antiferromagnetic coupling between two iron(iii) centers. Cyclic voltammetry measurements showed two kinds of quasireversible events, suggesting the formation of a phenoxyl radical species in the region of the anodic peaks and a metal-centered redox (FeIII/FeII) process at low potential. The catalytic activity of this Fe-complex was evaluated in coupling of 2-aminophenol and benzyl alcohols for the one-pot synthesis of benzoxazoles. The catalyst system showed high catalytic activity in this transformation and benzoxazole derivatives were obtained in good to excellent yields. tert-Butyl hydroperoxide was used as an oxidant and 1.2 mol% of catalyst was needed to accomplish the reaction in water as the green solvent.
- Safaei, Elham,Alaji, Zahra,Panahi, Farhad,Wojtczak, Andrzej,Jagli?i?, Janez Zvonko
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supporting information
p. 7230 - 7236
(2018/05/07)
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- One-pot green synthesis of benzoxazole derivatives through molecular sieve-catalyzed oxidative cyclization reaction
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An one-pot approach to benzoxazole ring from 2-aminophenol and aldehydes utilizing molecular sieve as the catalyst have been developed. The new oxidative cyclization reaction excluded the usage of hazardous chemical reagents, transition-metal catalysts, chemical oxidants, or strong acids, and, therefore, reduced the production of toxic chemical waste. This offers an environmentally friendly pathway for the synthesis of various benzoxazole derivatives.
- Chang, Weichieh,Sun, Yukai,Huang, Yungtzung
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- Microwave Assisted Synthesis of Two-Substituted Benzoxazoles in the Presence of Potassium Cyanide under Mild Conditions
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Various two-substituted benzoxazoles were prepared using microwave-assisted reaction of 2-aminophenol with aromatic aldehydes in the presence of one equivalent of potassium cyanide as an equimolecular catalyst. Aldehydes having either electron-donating or withdrawing groups afforded the target products. The important features of this method were high yields, short reaction times and easy work up. The structure of synthesized products was characterized by nuclear magnetic resonance (NMR) and infrared (IR).
- Naeimi, Hossein,Rahmatinejad, Soraya
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p. 471 - 476
(2015/11/02)
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- A mild, efficient and reusable solid phosphotungestic acid catalyst mediated synthesis of benzoxazole derivatives: A grinding approach
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Background: The development of efficient methodologies for the preparation of benzoxazole and its derivatives has gained a lot of importance in current research. There are many methods are reported for the synthesis of benzoxazoles includes condensation of 2-aminophenol with carboxylic acid. Traditional methods also have several side reactions, non renewable oxidative reagents and solvents which negatively affect the environmentally and eco-friendly nature of the reaction. We have developed PTA catalyzed synthesis of 2-arylbenzoxazole from 2-aminophenols with different aromatic aldehydes using a grinding strategy in excellent yield. Methods: The synthesis of benzoxazoles in high yields by using silica supported Rangappa S. Keri PTA/PTA as solid acid catalyst at room temperature using grinding method. Results: Aromatic aldehydes which have electron donating or electron withdrawing groups were also investigated and as expected it gives good to excellent yield of products, it can be seen that electron donating and electron withdrawing groups does not show any difference on their action yields. Conclusion: We have developed PTA catalyzed synthesis of 2-arylbenzoxazole from 2-aminophenols with different aromatic aldehydes using a grinding strategy in excellent yield. The use of this reusable catalyst under solvent-free conditions has made this protocol practical, environmentally friendly and economically attractive. The simple work-up procedure, the short reaction times the mild reaction conditions, the high yields of products and the non-toxicity of the catalyst are other advantages of the present method. This protocol approaches combines the advantages of both focused library synthesis and diversity oriented synthesis because of the simplification of reaction protocol that we have been developed.
- Patil, Mahadeo R.,Yelamaggad, Aditya,Keri, Rangappa S.
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p. 474 - 481
(2016/11/19)
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- Graphene oxide as a heterogeneous reagent promoted synthesis of 2-substituted 1,3-benzazoles in water
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An efficient chemical method for the synthesis of benzimidazoles, benzothiazoles, and benzoxazoles has been developed through the condensation of various aldehydes with o-phenylenediamine, o-aminothiophenol, and o-aminophenol using graphene oxide (GO) as an oxidant in water. These benzazoles are also prepared through a one-pot oxidation/condensation tandem process by reacting alcohols with 2-amino-(thio)phenol/aniline in the presence of GO in poly(ethylene glycol) as a safe media. Moreover, this carbonaceous material could be readily separated using a simple filtration.
- Khalili, Dariush,Banazadeh, Ali Reza
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p. 1693 - 1706
(2016/01/26)
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- Magnetically separable nano CeO2: A highly efficient catalyst for ligand free direct C-H arylation of heterocycles
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An efficient, ligand free, nano CeO2-Fe3O4 catalyzed direct C-H arylation of heteroarenes such as benzoxazole and benzothiazole has been carried out with aryl halides in DMSO or arenediazonium salts in water. The catalyst exhibited high activity with moderate to excellent product yields under mild reaction conditions. Nano CeO2-Fe3O4 was synthesized and characterized by SEM, TEM, EDAX, XRD, FTIR, DSC-TGA, and ICP-MS analyses. The catalytic activity and stability of the catalyst were excellent, even after the ten cycle of recyclability
- Shelkar, Radheshyam S.,Balsane, Kishor E.,Nagarkar, Jayashree M.
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supporting information
p. 693 - 699
(2015/01/30)
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- An efficient magnetic copper ferrite nanoparticle: For one pot synthesis of 2-substituted benzoxazole via redox reactions
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A new, green and sustainable approach for the synthesis of 2-substituted benzoxazole by using a one pot redox cascade condensation reaction of benzyl amine and 2-nitro phenol, catalysed by Cu Ferrite NPs is reported. Cu Ferrite NPs are magnetically separable, air stable and can be recycled up to fifth cycle without a significant loss in catalytic activity. The catalyst is characterised by FEG-SEM, TEM, EDAX and XRD.
- Sarode, Sachin A.,Bhojane, Jeevan M.,Nagarkar, Jayashree M.
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supporting information
p. 206 - 210
(2015/02/02)
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- Synthesis and pharmacological evaluation of piperidine (piperazine)-substituted benzoxazole derivatives as multi-target antipsychotics
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The present study describes the optimization of a series of novel benzoxazole-piperidine (piperazine) derivatives combining high dopamine D2 and serotonin 5-HT1A, 5-HT2A receptor affinities. Of these derivatives, the pharm
- Huang, Ling,Zhang, Wenjun,Zhang, Xiaohua,Yin, Lei,Chen, Bangyin,Song, Jinchun
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supporting information
p. 5299 - 5305
(2015/11/09)
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- Ruthenium-catalyzed synthesis of benzoxazoles using acceptorless dehydrogenative coupling reaction of primary alcohols with 2-aminophenol under heterogeneous conditions
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An efficient ruthenium-catalyzed acceptorless dehydrogenative coupling reaction of primary alcohols with 2-aminophenol for one-pot synthesis of benzoxazoles is introduced. The phosphine-functionalized magnetic nanoparticles (PFMNPs; Fe3O4@SiO2@PPh2) as a magnetic recyclable phosphorus ligand in the presence of Ru2Cl 4(CO)6 was found to be an efficient heterogeneous catalytic system for promotion of the designed protocol. The reaction was carried out efficiently with a variety of substrates to give the corresponding products in moderate to good yields.
- Khalafi-Nezhad, Ali,Panahi, Farhad
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p. 1686 - 1692
(2014/06/24)
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- Magnetic nanoparticles-supported tungstosilicic acid: As an efficient magnetically separable solid acid for the synthesis of benzoazoles in water
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The magnetic nanoparticles-supported tungstosilicic acid (TSAMNP) was found to be a highly efficient solid acid for the synthesis of benzoazoles in water. TSAMNP catalyst was achieved by the immobilization of tungstosilicic acid [H4(W12SiO40)] species on the silica core-shell magnetic nanoparticles (Fe3O4@SiO2). A variety of aldehydes were successfully condensed with 1,2-diaminobenzene, 2-aminophenol and 2-aminothiophenol in water as a green solvent to synthesize benzoazoles in good-to-excellent yields. TSAMNP catalyst was easily separated from the reaction mixture and reused several times without any loss of efficiency.
- Khalafi-Nezhad, Ali,Panahi, Farhad,Yousefi, Reza,Sarrafi, Sina,Gholamalipour, Yasaman
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p. 1311 - 1319
(2014/11/07)
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- A ball-milling strategy for the synthesis of benzothiazole, benzimidazole and benzoxazole derivatives under solvent-free conditions
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A convenient solvent-free method for the synthesis of benzothiazole, benzimidazole, and benzoxazole derivatives has been developed using recyclable ZnO-NPs via a ball-milling strategy. The method affords environmentally friendly reaction conditions that score high on the ecoscale with the low E-factor. The process is also highly efficient even on a multi-gram scale and provides easy product isolation.
- Sharma, Hemant,Singh, Narinder,Jang, Doo Ok
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p. 4922 - 4930
(2015/01/08)
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- Nano ceria catalyzed synthesis of substituted benzimidazole, benzothiazole, and benzoxazole in aqueous media
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A series of substituted benzimidazoles, benzothiazoles, and benzoxazoles was synthesized by combining 1,2-phenylenediamine, 2-aminothiophenol, or 2-aminophenol with aryl, heteroaryl, aliphatic, α,β-unsaturated aldehydes in the presence of nano ceria (CeO2) as an efficient heterogeneous catalyst.
- Shelkar, Radheshyam,Sarode, Sachin,Nagarkar, Jayashree
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supporting information
p. 6986 - 6990
(2013/12/04)
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- Zn(OAc)2 · 2H2O-catalyzed, simple, and clean procedure for the synthesis of 2-substituted benzoxazoles using a grindstone method
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Zn(OAc)2 · 2H2O efficiently catalyzes the condensation reaction between 2-aminophenol and various araldehydes to afford the 2-substituted benzoxazoles in good to excellent yields. The remarkable features of this protocol are simple and mild reaction conditions, use of readily available catalyst, and shorter reaction time, and in addition the reaction proceeds just by grinding the substrates and catalyst without any solvent and hence matches the green chemistry protocols.
- Madhusudana Reddy,Nizam, Aatika,Pasha
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experimental part
p. 1838 - 1842
(2011/06/23)
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- Dess-martin periodinane mediated intramolecular cyclization of phenolic azomethines: A solution-phase strategy toward benzoxazoles and benzothiazoles
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Dess-Martin periodinane (DMP), a highly versatile hypervalent iodine(V) reagent, was found to efficiently mediate the intramolecular cyclization of phenolic azomethines/Schiff bases at ambient temperature leading to the rapid and expeditious synthesis of substituted benzoxazoles and benzothiazoles. Furthermore, a solution-phase strategy has been developed by treating the reaction mixtures sequentially with Amberlyst A-26 thiosulfate resin and diisopropylaminomethyl resin (PS-DIEA), which remove excess reagent and byproducts, to give pure products. Georg Thieme Verlag Stuttgart - New York.
- Bose, D. Subhas,Idrees, Mohd.
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experimental part
p. 398 - 402
(2010/04/03)
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- Chiral 3-(4,5-dihydrooxazol-2-yl)phenyl alkylcarbamates as novel FAAH inhibitors: Insight into FAAH enantioselectivity by molecular docking and interaction fields
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Fatty acid amide hydrolase (FAAH) and monoglyceride lipase (MGL) are the main enzymes responsible for the hydrolysis of endogenous cannabinoids N-arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG), respectively. Phenyl alkylcarbamates are FA
- Myllymaeki, Mikko J.,Kaesnaenen, Heikki,Kataja, Antti O.,Lahtela-Kakkonen, Maija,Saario, Susanna M.,Poso, Antti,Koskinen, Ari M.P.
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experimental part
p. 4179 - 4191
(2009/12/04)
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- Biochemical and structural evaluation of highly selective 2-arylbenzoxazole-based transthyretin amyloidogenesis inhibitors
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To develop potent transthyretin (TTR) amyloidogenesis inhibitors that also display high binding selectivity in blood, it proves useful to systematically optimize each of the three substructural elements that comprise a typical inhibitor: the two aryl rings and the linker joining them. In the first study, described herein, structural modifications to one aryl ring were evaluated by screening a library of 2-arylbenzoxazoles bearing thyroid hormone-like aryl substituents on the 2-aryl ring. Several potent and highly selective amyloidogenesis inhibitors were identified that exhibit minimal thyroid hormone nuclear receptor and COX-1 binding. High resolution crystal structures (1.3-1.5 ?) of three inhibitors (2f, 4f, and 4d) in complex with TTR were obtained to characterize their binding orientation. Collectively, the results demonstrate that thyroid hormone-like substitution patterns on one aryl ring lead to potent and highly selective TTR amyloidogenesis inhibitors that lack undesirable thyroid hormone receptor or COX-1 binding.
- Johnson, Steven M.,Connelly, Stephen,Wilson, Ian A.,Kelly, Jeffery W.
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p. 260 - 270
(2008/09/18)
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