- Substituent dependence of imidazoline derivatives on the capture and release system of carbon dioxide
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The reversible capture-release behaviors of CO2 by imidazoline derivatives bearing several 2-substituents were investigated under dry conditions containing a very small amount of water. The imidazoline having a cyclic guanidine moiety only captured CO2 quantitatively, and then the cyclic guanidine derivative gave the guanidinium bicarbonate by CO2 fixation together with a slight amount of water. In contrast, the imidazolines bearing n-butylthiol and n-pentyl groups never captured CO2 even with the addition of an equimolar amount of water. Furthermore, the binding structure between CO2 and the cyclic guanidine derivative was studied in detail by elemental analysis, FTIR-ATR, solid-state NMR, TGA, and DFT calculations in order to predict the CO2 capture-release mechanisms depending on the imidazoline structure.
- Yoshida, Yoshiaki,Aoyagi, Naoto,Endo, Takeshi
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- Tandem copper catalyzed regioselectiveN-arylation-amidation: synthesis of angularly fused dihydroimidazoquinazolinones and the anticancer agent TIC10/ONC201
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Herein, we present a copper-catalyzed tandem reaction of 2-aminoimidazolines andortho-halo(hetero)aryl carboxylic acids that causes the regioselective formation of angularly fused tricyclic 1,2-dihydroimidazo[1,2-a]quinazolin-5(4H)-one derivatives. The reaction involved in the construction of the core six-membered pyrimidone moiety proceededviaregioselectiveN-arylation-condensation. The presented protocol been successfully applied to accomplish the total synthesis of TIC10/ONC201, which is an active angular isomer acting as a tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL): a sought after anticancer clinical agent.
- Honnanayakanavar, Jyoti M.,Nanubolu, Jagadeesh Babu,Suresh, Surisetti
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supporting information
p. 8497 - 8501
(2021/10/20)
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- Synthesis of five- and six-membered cyclic guanidines by guanylation with isothiouronium iodides and amines under mild conditions
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Cyclic guanidine hydroiodides were obtained in one step by the reactions of isothiouronium iodides with an equimolar amount of various amines in tetrahydrofuran. The obtained hydroiodides were neutralized with sodium hydroxide or anionic exchange resin to afford the corresponding substituted cyclic guanidines in quantitative yields.
- Aoyagi, Naoto,Endo, Takeshi
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supporting information
p. 442 - 448
(2017/02/24)
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- High-Field NMR Spectroscopy Reveals Aromaticity-Modulated Hydrogen Bonding in Heterocycles
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From DNA base pairs to drug–receptor binding, hydrogen (H-)bonding and aromaticity are common features of heterocycles. Herein, the interplay of these bonding aspects is explored. H-bond strength modulation due to enhancement or disruption of aromaticity of heterocycles is experimentally revealed by comparing homodimer H-bond energies of aromatic heterocycles with analogs that have the same H-bonding moieties but lack cyclic π-conjugation. NMR studies of dimerization in C6D6 find aromaticity-modulated H-bonding (AMHB) energy effects of approximately ±30 %, depending on whether they enhance or weaken aromatic delocalization. The attendant ring current perturbations expected from such modulation are confirmed by chemical shift changes in both observed ring C?H and calculated nucleus-independent sites. In silico modeling confirms that AMHB effects outweigh those of hybridization or dipole–dipole interaction.
- Kakeshpour, Tayeb,Bailey, John P.,Jenner, Madison R.,Howell, Darya E.,Staples, Richard J.,Holmes, Daniel,Wu, Judy I.,Jackson, James E.
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supporting information
p. 9842 - 9846
(2017/08/08)
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- C-N Bond forming reactions in the synthesis of substituted 2-aminoimidazole derivatives
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Carbon-nitrogen bond forming reactions oriented to the synthesis of 2-amino-imidazolidines and imidazoles have been investigated. The C-2 amination of imidazolidinones, via the corresponding 2-chlorodihydroimidazoles, led to 2-benzylaminodihydroimidazole or bis(dihydroimidazole)amino derivatives by choosing the adequate experimental conditions. On the other hand, the use of N-acyl-2-methylsulfanyldihydroimidazoles allowed carrying out the reactions with aromatic amines, such as p-anisidine. Finally, palladium catalyzed Buchwald- Hartwig amination was the method of choice for C-N coupling between 2-haloimidazoles and aromatic amines in the synthesis of the corresponding imidazoles.
- Gomez-SanJuan, Asier,Botija, Jose Manuel,Mendez, Almudena,Sotomayor, Nuria,Letea, Esther
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- Microwave-induced synthesis of 2-aminoimidazolines under neat conditions
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2-Aminoimidazolines were synthesized by the nucleophilic substitution reaction of 2-methylmercapto-4,5-dihydroimidazole hydroiodide with various amine compounds under neat conditions. Copyright Taylor & Francis Group, LLC.
- Genc, Murat,Servi, Sueleyman
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scheme or table
p. 3263 - 3277
(2011/03/18)
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- N-nitroso- and N-nitraminotetrazoles
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N-Nitroso- (5a,c) and N-nitraminotetrazoles (6a-c) were synthesized from the corresponding aminotetrazoles (3a-c) either by the direct nitration with acetic anhydride/HNO3 or by dehydration of the corresponding nitrates (4a-c) with concentrated sulfuric acid. The conversion of the N-nitrosoaminotetrazoles (5a,c) with peroxytrifluoroacetic acid (CF 3CO3H) yielded the corresponding nitramines in high yield (6a (82%), 6c (80%)). The N-nitroso- (5a,c) and N-nitraminotetrazoles (6a-c) have been fully characterized by vibrational (IR, Raman) and multinuclear NMR spectroscopy (14N/15N, 1H, 13C), mass spectrometry, and elemental analysis. A detailed discussion of the 15N chemical shifts and 1H-15N coupling constants is given. The molecular structures in the solid state were determined by single-crystal X-ray diffraction (3a,c; 5a,c; 6a-c) and a detailed discussion of the molecular structures will be presented. Furthermore, the structure and bonding as well as N,N rotational barriers are discussed on the basis of theoretically obtained data (B3LYP/6-31G(d,p), NBO analysis). In the case of two N-nitraminotetrazoles (6a,c) the physicochemical properties (e.g., D, P, ΔfH°) were evaluated. The heat of formation was calculated to be positive for 6a and 6c (+2.8 and +85.2 kcal mol-1, respectively) and the calculated detonation velocity with 5988 (6a) and 7181 (6c) m s-1 reaches values of TNT and nitroglycerin.
- Karaghiosoff, Konstantin,Klapoetke, Thomas M.,Mayer, Peter,Piotrowski, Holger,Polborn, Kurt,Willer, Rodney L.,Weigand, Jan J.
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p. 1295 - 1305
(2007/10/03)
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- PEPTIDOMIMETICS SELECTIVE FOR THE SOMATOSTATIN RECEPTOR SUBTYPES 1 AND/OR 4
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The invention relates to (hetero)arylsulfonylamino based peptidomimetics of formula (I), wherein A, D, E, J, Q1 R1 , R2, R3, p and j are defined as disclosed, or a pharmaceutically acceptable salt or ester thereof. Compounds of formula (I) possess high affinity and selectivity for the somatostatin receptor subtypes sst1 and/or sst4 and can be used for the treatment or diagnosis of diseases or conditions wherein sst1 and/or sst4 agonists or antagonists are indicated to be useful.
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Page/Page column 72-73
(2010/11/24)
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- I(2)-imidazoline binding site affinity of a structurally different type of ligands.
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Two families of compounds with affinity towards the I(2) imidazoline binding sites are reported. The first is a family of compounds structurally related to agmatine with two guanidine or 2-aminoimidazoline groups at each end of an aliphatic chain of six,
- Dardonville, Christophe,Rozas, Isabel,Callado, Luis F,Meana, J Javier
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p. 1525 - 1533
(2007/10/03)
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- Is there stereoelectronic control in hydrolysis of cyclic guanidinium ions?
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To assess stereoelectronic effects in the cleavage of tetrahedral intermediates, a series of five-, six-; and seven-membered cyclic guanidinium salts was synthesized. If stereoelectronic control by antiperiplanar lone pairs is operative, these are expected to hydrolyze with endocyclic C-N cleavage to acyclic ureas. However, hydrolysis in basic media produces mixtures of cyclic and acyclic products, as determined by 1H NMR analysis. The results show that in the six-membered ring antiperiplanar lone pairs provide a weak acceleration of the breakdown of the tetrahedral intermediate, but in five- and seven-membered rings there is no evidence for such acceleration, which instead can be provided by syn lone pairs.
- Perrin,Young
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p. 4446 - 4450
(2007/10/03)
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- Syntheses and Spectral Properties of 2-Thiobiotin and Biotin Derivatives
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A series of methylated derivatives of 2-thiobiotin (2-4) have been prepared as potential aids in elucidation of the mechanism of biotin catalysis.The syntheses and mass, infrared, 1H nmr, and 13C nmr spectral properties for these substrates, their 2-thiobiotin precursors (6,10-14) and the corresponding biotin analogs (1,15,31-34) are described.A series of selective proton-proton and proton-carbon decoupling experiments were employed to secure a number the 1H and 13C nmr assignments.Consistent patterns noted throughout the data set proved helpful in structure determination.
- Flaster, Harry,Kohn, Harold
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p. 1425 - 1436
(2007/10/02)
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