- Unexpected Decarboxylation-Triggered o-Hydroxyl-Controlled Redox Condensation of Phenylglycines with 2-Nitrophenols in Aqueous Media
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A decarboxylation-triggered and o-hydroxyl-controlled hydrogen-transfer strategy for the one-pot synthesis of benzoxazoles from readily available amino acids and 2-nitrophenols is reported. On the basis of this autoredox reaction, the C?N bond can be efficiently constructed to afford the desired products in moderate to good yields under transition-metal-free conditions in aqueous media. (Figure presented.).
- Tang, Lin,Yang, Zhen,Sun, Tian,Zhang, Di,Ma, Xiantao,Rao, Weihao,Zhou, Yuqiang
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supporting information
p. 3055 - 3062
(2018/08/01)
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- Design, Synthesis, and Biological Activity of New N -(Phenylmethyl)-benzoxazol-2-thiones as Macrophage Migration Inhibitory Factor (MIF) Antagonists: Efficacies in Experimental Pulmonary Hypertension
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Macrophage migration inhibitory factor (MIF) is a key pleiotropic mediator and a promising therapeutic target in cancer as well as in several inflammatory and cardiovascular diseases including pulmonary arterial hypertension (PAH). Here, a novel series of N-(phenylmethyl)-benzoxazol-2-thiones 5-32 designed to target the MIF tautomerase active site was synthesized and evaluated for its effects on cell survival. Investigation of structure-activity relationship (SAR) particularly at the 5-position of the benzoxazole core led to the identification of 31 that potently inhibits cell survival in DU-145 prostate cancer cells and pulmonary endothelial cells derived from patients with idiopathic PAH (iPAH-ECs), two cell lines for which survival is MIF-dependent. Molecular docking studies helped to interpret initial SAR related to MIF tautomerase inhibition and propose preferred binding mode for 31 within the MIF tautomerase active site. Interestingly, daily treatment with 31 started 2 weeks after a subcutaneous monocrotaline injection regressed established pulmonary hypertension in rats.
- Le Hiress, Morane,Akagah, Bernardin,Bernadat, Guillaume,Tu, Ly,Thuillet, Rapha?l,Huertas, Alice,Phan, Carole,Fadel, Elie,Simonneau, Gérald,Humbert, Marc,Jalce, Ga?l,Guignabert, Christophe
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p. 2725 - 2736
(2018/04/23)
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- Oxidative NHC Catalysis for the Generation of Imidoyl Azoliums: Synthesis of Benzoxazoles
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N-Heterocyclic carbene (NHC)-catalyzed intramolecular cyclization of aldimines generated from 2-amino phenols and aromatic aldehydes leading to the synthesis of 2-arylbenzoxazoles under mild conditions is presented. The reaction proceeds via the generation of the aza-Breslow intermediates from imines and NHC, which under oxidative conditions form the key imidoyl azoliums and a subsequent intramolecular cyclization furnishes the product. The reaction tolerates a broad range of functional groups, and the products are formed in generally good yields.
- Patra, Atanu,James, Anjima,Das, Tamal Kanti,Biju, Akkattu T.
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p. 14820 - 14826
(2019/01/03)
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- Cyanide as a powerful catalyst for facile synthesis of benzofused heteroaromatic compounds via aerobic oxidation
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Highly efficient synthesis of benzofused heteroaromatic compounds via aerobic oxidation catalyzed by cyanide anion has been developed. The Schiff bases derived from 2-aminophenol and aldehydes provided the corresponding benzoxazoles in high yields in the presence of a catalytic amount of cyanide in an open flask under ambient conditions without the use of any external metal co-oxidants and bases. Furthermore, we have developed a catalytic sequential one-step protocol for the synthesis of benzoxazoles by adding a catalytic amount of NaCN to Schiff bases generated in situ from 2-aminophenol and aldehydes without the isolation of imine intermediates. This one-pot protocol was further extended to the synthesis of benzothiazoles from 2-aminothiophenol and aldehydes. A variety of aldehydes could be applied to this sequential one-pot protocol and the desired benzofused azole products were obtained in high yields.
- Cho, Yeon-Ho,Lee, Chun-Young,Cheon, Cheol-Hong
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p. 6565 - 6573
(2013/07/26)
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- Cyanide as a powerful catalyst for facile preparation of 2-substituted benzoxazoles via aerobic oxidation
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A cyanide-catalyzed synthesis of 2-substituted benzoxazoles from Schiff bases via aerobic oxidation has been developed. The products from various Schiff bases were obtained in high yields in an open flask under ambient conditions without other external oxidants. We have also developed a simple one-step protocol for the synthesis of benzoxazoles from aminophenol and the corresponding aldehydes in the presence of cyanide without isolation of imine intermediates. Copyright
- Cho, Yeon Ho,Lee, Chun-Young,Ha, Deok-Chan,Cheon, Cheol-Hong
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supporting information
p. 2992 - 2996
(2013/01/15)
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- Facile preparation of 2-substituted benzoxazoles and benzothiazoles via aerobic oxidation of phenolic and thiophenolic imines catalyzed by polymer-incarcerated platinum nanoclusters
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Platinum nanoclusters supported on a polymer/carbon black composite material was found to be an excellent catalyst for the oxidative cyclization of phenolic and thiophenolic Schiff bases to 2-substituted benzoxazoles and benzothiazoles under ambient conditions. Copyright
- Yoo, Woo-Jin,Yuan, Hao,Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information; experimental part
p. 3085 - 3089
(2012/01/02)
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- Selective alkylation of aminophenols
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O-or N-Alkylated derivatives of aminophenols are important synthetic intermediates in organic synthesis. A series of aminophenols were selectively alkylated on their hydroxyl group in good yields via benzaldehyde protection of the amino group, subsequent alkylation, and hydrolysis; or on their amino group via imination and following reduction. ARKAT USA, Inc.
- Wang, Renchao,Xu, Jiaxi
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experimental part
p. 293 - 299
(2010/10/02)
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- Iodine (III)-mediated synthesis of some 2-aryl/ hetarylbenzoxazoles as antibacterial/antifungal agents
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Ten 2-aryl/hetarylbenzoxazoles (5a, 5b, and 6a-h) were synthesized via oxidative cyclization of Schiff bases (3a, 3b, and 4a-h) with 1.1 equivalent of iodobenzene diacetate (IBD) in methanol. All of these 2-aryl/hetarylbenzoxazoles (5a, 5b, and 6a-h) were tested in vitro for their antibacterial and antifungal activities against Bacillus subtilis, Bacillus stearothermophilus, Escherichia coli, and Pseudomonas putida. These compounds also were screened for their antifungal activity against Aspergillus flavus and Aspergillus niger. Biological activity of these compounds was compared with those of commercially available antibiotics, chloramphenicol and antifungal agent cycloheximide. Most of these compounds, 5a, 5b, 6a, 6b, 6d, 6e, 6g, 6h, were equipotent or more potent than these commercial drugs at concentration 100 μg/ml. Birkhaeuser Boston 2009.
- Kumar, Ravi,Nair, Reshmi R.,Dhiman, Saurabh Sudha,Sharma, Jitender,Prakash, Om
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experimental part
p. 541 - 550
(2011/11/01)
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- Hypervalent iodine(III) mediated synthesis of 2-substituted benzoxazoles
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2-Substituted benzoxazoles (6a-j, 7a-e, 7j-l) have been synthesized via the oxidative intramolecular cyclization of Schiff's bases (4a-j, 5a-e, 5j-l) using iodobenzene diacetate (IBD) as an oxidant in dry methanol. A one-pot procedure for the synthesis of 6a-j, 7a-e and 7j-l starting from o-aminophenol/p-chloro-o- aminophenol and aldehydes has also been developed.
- Prakash, Om,Batra, Anita,Sharma, Vijay,Saini, Rajesh K.,Verma, Rajender S.
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p. 1031 - 1034
(2007/10/03)
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