- Environmentally benign strategy for arylation of nitronyl nitroxide using a non-Transition metal nucleophile
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We have developed a method for the arylation of nitronyl nitroxide without using its transition metal complex as a nucleophile. Various nitronyl nitroxide-substituted I -electronic compounds can be obtained from the parent nitronyl nitroxide and the corresponding aryl iodides using a combination of zero-valent palladium catalysts and a 2-dicyclohexylphosphino-2′,4′,6′-Triisopropylbiphenyl ligand in the presence of sodium tert-butoxide. The utility of the method has been demonstrated by the direct synthesis of open-shell compounds with giant I -electronic systems, such as 10P.
- Nakamura, Fumiya,Naota, Takeshi,Suzuki, Shuichi
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supporting information
p. 1350 - 1354
(2020/03/13)
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- Radical metalloids with N-heterocyclic carbene and phenanthroline ligands: Synthesis, properties, and cross-coupling reaction of [(nitronyl nitroxide)-2-ido]metal complexes with aryl halides
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New radical metalloids, NN-AuSIMes and NNCu( bdmpphen), were prepared and their properties were investigated. They were applied to Pd(0)-mediated crosscoupling reactions with aryl halides (ArX) to produce 2-aryl (nitronyl nitroxide) s in moderate to high
- Yamada, Kiyomi,Zhang, Xun,Tanimoto, Ryu,Suzuki, Shuichi,Kozaki, Masatoshi,Tanaka, Rika,Okada, Keiji
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p. 1150 - 1157
(2018/07/29)
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- Synthesis and Straightforward Quantification Methods of Imino Nitroxide-Based Hexaradical Architecture on a Cyclotriphosphazene Scaffold
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The synthesis of a homogeneous neutral hexaradical architecture consisting of six imino nitroxide radical moieties covalently bonded on a cyclotriphosphazene scaffold was reported. The synthesis of hexaradical imino nitroxide compounds follows the Ullman procedure involving the condensation of 2,3-bis(hydroxylamino)-2,3-dimethylbutane with hexa-(4-formylphenoxy)cyclotriphosphazene (3) followed by oxidation of the condensation product hexa-[4-(1-hydroxy-4,4,5,5-tetramethyl-2-imidazoline-2-yl)phenoxy]cyclotriphosphazene (2) by NaIO4. Characterization of hexaradical was performed by X-ray and SQUID in solid state and by EPR, absorption spectroscopy, and electrochemistry in solution. CV of 1 shows an oxidation peak at 1.184 V (vs SCE) and a reduction peak at -0.883 V, both characteristics of the presence of phenyl imino nitroxide (7) moieties, suggesting that the contribution of the cyclotriphosphazene core is negligible. Attention was particularly focused on developing methods, UV-vis spectroscopy and square-wave voltammetry, to quantify the number of radicals in a way to confirm easily and rapidly the polyradicals' structure.
- Fidan, Ismail,?nal, Emel,Yerli, Yusuf,Luneau, Dominique,Ahsen, Vefa,Hirel, Catherine
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supporting information
p. 11447 - 11453
(2016/11/17)
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- Nitronyl nitroxide as a coupling partner: Pd-mediated cross-coupling of (nitronyl nitroxide-2-ido)(triphenylphosphine)gold(i) with aryl halides
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A cross-coupling reaction using nitronyl nitroxide (NN) as a coupling partner was developed: Refluxing a mixture of [AuI(NN-2-ido)(PPh3)] and aryl iodide (ArI) in THF in the presence of 10 mol% [Pd(PPh3)4] produced a cross-coupling product NN-Ar in a high yield. This method allowed the direct introduction of the NN radical onto various poly- and heterocyclic aromatic rings.
- Tanimoto, Ryu,Suzuki, Shuichi,Kozaki, Masatoshi,Okada, Keiji
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supporting information
p. 678 - 680
(2014/05/20)
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- A class of novel nitronyl nitroxide labeling basic and acidic amino acids: Synthesis, application for preparing ESR optionally labeling peptides, and bioactivity investigations
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Aimed at optional ESR label 2-(4′-hydroxyl)phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl was introduced into the guanido of l-Arg-OH, the ω-amino group of l-Lys-OH with methylcarboxyl as a linker, and into the β-carboxyl of l-Asp-OH and the γ-carboxyl of l-Glu-OH with ethylamino as a linker. It was explored that the synthetic 30 novel ESR labeling amino acid derivatives were stable enough to the reaction conditions of peptide synthesis. Their incorporation led to 12 novel ESR optionally labeling PAK, RGDS, RGDV, and ECG. A series of NO related chemical tests, the in vitro and in vivo assays of these peptides confirmed that this strategy was practical.
- Zhang, Jianwei,Zhao, Ming,Cui, Guohui,Peng, Shiqi
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p. 4019 - 4028
(2008/12/22)
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- 1,3-Alternate calix[4]arene nitronyl nitroxide tetraradical and diradical: synthesis, X-ray crystallography, paramagnetic NMR spectroscopy, EPR spectroscopy, and magnetic studies
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Calix[4]arenes constrained to 1,3-alternate conformation and functionalized at the upper rim with four and two nitronyl nitroxides have been synthesized, and characterized by X-ray crystallography, magnetic resonance (EPR and 1H NMR) spectroscopy, and magnetic studies. Such calix[4]arene tetraradicals and diradicals provide scaffolds for through-bond and through-space intramolecular exchange couplings.
- Rajca, Andrzej,Pink, Maren,Mukherjee, Sumit,Rajca, Suchada,Das, Kausik
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p. 10731 - 10742
(2008/02/13)
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- Novel 1-oxyl-2-substitutedphenyl-4,4,5,5-tetramethylimidazolines: Synthesis, selectively analgesic action, and QSAR analysis
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Based on the knowledge that imidazoline can result in analgesic action due to its selective binding with the prostacyclin receptor, 20 1-oxyl-2-substitutedphenyl-4,4,5,5-tetramethylimidazolines (3a-t) were prepared in moderate yields. At 0.13 mmol/kg dose, their in vivo analgesic activities were evaluated after the mice were administered at 30, 60, 90, and 150 min. Compared with the pain threshold (12.27 ± 9.56-17.71 ± 7.00%) of normal saline (NS) receiving mice, the pain threshold (23.42 ± 8.14% to 102.58 ± 10.66%) of 3a-t receiving mice increases significantly. Considering a prostacyclin receptor targeting analgesic agent usually had bleeding action and to appraise the bleeding risk, the in vivo tail bleeding time of 1.30 mmol/kg 3a-t receiving mice was found to be ranged from 116.3 ± 8.2 s to 120.3 ± 9.2 s, which was substantially equal to that (117.8 ± 8.4 s to 119.0 ± 8.6 s) of NS receiving mice. Based on the possibility of imidazoline acting as vasodilator, the in vitro vasorelaxations of 3a-t were tested using the rat aortic strip model. When the aortic strip contracted by noradrenaline (NE, final concentration 10-7 mol/l) was treated with 3a-t (final concentration 5 × 10-4 mol/l), only lower percentage inhibitions (6.55 ± 5.70-37.40 ± 4.07%) were recorded, implying that the vasorelaxation of 3a-t was neglectable. By selecting appropriate molecular descriptors generated from e-dragon server, the QSAR model of the analgesic activities of 3a-t was constructed using the multiple linear regression method. The established QSAR model showed reasonable accuracy and thus it is promising to be used for screening new 1-oxyl-2-substitutedphenyl-4,4,5,5-tetramethylimidazoline derivatives as analgesic agents.
- Zhao, Ming,Li, Zheng,Peng, Li,Tang, Yu-Rong,Wang, Chao,Zhang, Ziding,Peng, Shiqi
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p. 2815 - 2826
(2007/10/03)
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- Novel 2-substituted nitronyl nitroxides as free radical scavengers: Synthesis, biological evaluation and structure-activity relationship
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To develop more potent small molecules with enhanced free radical scavenger properties, we designed and synthesized a series of nitronyl nitroxide derivatives 4a-h. A lead compound 4f was discovered based on Ach-induced vascorelaxation assay. Further chemical modification based on this scaffold provided a new series of 2-substituted phenylnitronyl nitroxide derivatives 6a-s. The newly synthesized compounds 6a-s possess improved radical scavenger's activity based on PC12 cell survival assay. Compounds 6g,n,o, and s are some of the most potent compounds in terms of NO, H2O2, and OH scavenging ability. 2-Substitued phenylnitronyl nitroxides had a higher radical scavenging activity with the electron-donating group (EDG). In contrast, the introduction of electron-withdrawing group (EWG) to the aromatic ring led to a dramatic decrease in its radical scavenging activity. These results suggest that the electron-donating group (EDG) of the aromatic ring may be an important factor influencing the radical scavenging behavior of these compounds, and the potency of free radical scavenging activity largely depended on the position and electronic properties of the phenyl ring substituents. The enhanced radical scavenging capacities of the novel 2-substituted nitronyl nitroxides may be potential drug leads against the deleterious action of ROS (reactive oxygen species)/RNS (reactive nitrogen species).
- Wu, Yihui,Bi, Lanrong,Bi, Wei,Li, Zeng,Zhao, Ming,Wang, Chao,Ju, Jingfang,Peng, Shiqi
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p. 5711 - 5720
(2007/10/03)
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- Nitronyl and imino nitroxides: Improvement of Ullman's procedure and report on a new efficient synthetic route
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The synthesis of nitronyl and imino nitroxides has been reexamined with the aim of both increasing yields and of offering opportunities for new structures. The conditions for the formation of 2,3-bis(hydroxyamino)-2,3-dimethylbutane, the key intermediate of Ullman's route, have been carefully studied, and a new procedure is proposed, which affords the free base in a very pure form and up to 60% yield. Full characterization of this intermediate including an X-ray crystal structure is presented. An alternative synthetic route through 2,3-diamino-2,3-dimethylbutane and the corresponding imidazolidines which bypasses the delicate synthesis of the bis(hydroxyamino) compound is described. It is shown that 3-chloroperbenzoic acid is an effective oxidant for the transformation of adequately substituted imidazolidines into nitronyl nitroxides, which are obtained in high yield. An illustration of the potentialities of this new route, a new nitronyl nitroxide with two ethyl substituents in positions 4 and 5 of the imidazoline ring, is reported. The scope and limitations of the two routes are discussed.
- Hirel, Catherine,Vostrikova, Kira E.,Pecaut, Jacques,Ovcharenko, Victor I.,Rey, Paul
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p. 2007 - 2014
(2007/10/03)
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- Synthesis and reactions of new nitronyl nitroxides
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Various new 2-substituted 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-yloxyl 3-oxide mono- 1b, 7, 13a,b, 14, 15, 16, 17, 22 and biradicals 8, 9 were prepared. The nitronyl nitroxide functions were selectively reduced by Fe/HOAc to 1-hydroxyimidazoline derivatives 3b, 11, 21. The reductions by Zn/HCl led to imidazolines 4, 12. The nitronyl nitroxide functions remained inert when the 2-phenyl compound was nitrated by H2SO4/HNO3 to give nitrophenyl nitronyl nitroxide derivatives 13a,b, 14.
- Kálai, Tamás,Jeko, József,Szabó, Zoltán,Párkányi, László,Hideg, Kálmán
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p. 1049 - 1055
(2007/10/03)
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