- Efficient synthesis of novel 2,3-dihydro-1,3,5,4-thiadiazaphosphole derivatives
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ABSTRACT: The condensation of various thiosemicarbazones with methyl thiophene-2-carboximidate afforded the corresponding intermediates 2a–2h. Subsequent cyclization of the latter compounds with hexamethylphosphorous triamide constitutes a new route to the synthesis of novel highly functionalized thiadiazaphosphole derivatives 4a–4h. This method offers significant advantages such as efficiency, high yields and mild reaction conditions.
- Balti, Monaem,Efrit, Mohamed Lotfi
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p. 466 - 475
(2016/07/23)
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- Camphor-annelated imidazolines with various N1 and C2 pendants as tunable ligands for nitroaldol reactions
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Starting from (1R,2S,3R)-camphordiamine and (hetero)aromatic imidates and orthoformate, nine new camphor-annelated NH-imidazolines were synthesized. Subsequent N-modification was carried out via methylation, acylation, benzoylation, and sulfonylation. Two regioisomers were usually isolated with the ratios reflecting the structure of the starting NH-imidazoline and the electrophile used. All of the successfully prepared N1- and C2-substituted camphor-annelated imidazolines were applied to the asymmetric version of a Cu(II)-catalyzed Henry reaction. The electronic effects of both N1- and C2-pendants on the chemical and asymmetric outcomes of the nitroaldol reaction have been studied and discussed. 2012 Elsevier Ltd.
- Tydlitat, Jiri,Bures, Filip,Kulhanek, Jiri,Mloston, Grzegorz,Ruzicka, Ales
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scheme or table
p. 1010 - 1018
(2012/09/25)
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- 1,2-disubstituted hexahydro-1 H -benzo[d]imidazoles: Synthesis, characterization, and stability
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Starting from commercially available (hetero)aromatic nitriles and (1R,2R)-cyclohexane-1,2-diamine, nine NH-imidazolines (hexahydro-1H-benzo[d] imidazoles) were synthesized in good yields. The molecular structures of three imidazolines were confirmed by X-ray analysis. N-Benzylation afforded some of the desired N-benzylimidazolines, but was incompatible with imidazolines that possessed strong electron-accepting heteroaromatic groups at C2. In the latter cases, the products decomposed during column chromatography to form N,N-disubstituted cyclohexane-1,2-diamines. Georg Thieme Verlag Stuttgart · New York.
- Tydlitat, Jiri,Bures, Filip,Kulhanek, Jiri,Ruzicka, Ales
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scheme or table
p. 3934 - 3940
(2010/12/29)
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- Synthesis and evaluation of adenosine antagonist activity of a series of [1,2,4]triazolo[1,5-c]quinazolines
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A series of [1,2,4]triazolo[1,5-c]quinazolines were prepared in satisfactory yields by reaction of some derivatives of 2-aminobenzohydrazide with several hydrochlorides of aromatic amidines, and their binding affinities for the recombinant human adenosine A2A and A2B receptors were determined. None of the new compounds showed noteworthy affinity for these receptors, though a very high affinity for the A2A receptor and, consequently, a high level of A2A/A2B selectivity was revealed for one of the synthesized compounds.
- Balo, Carmen,Lopez, Carmen,Brea, Jose Manuel,Fernandez, Franco,Caamano, Olga
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p. 372 - 375
(2008/02/02)
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- Synthesis and Histamine H1 Receptor Agonist Activity of a Series of 2-Phenylhistamines, 2-Heteroarylhistamines, and Analogues
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New histamine derivatives characterized by a (substituted) aryl, heteroaryl, benzyl, or hetroarylmethyl substituent in the C2 position of the imidazole ring have been prepared from appropriate imidates or amidines, respectively, and 2-oxo-4-phthalimido-1-butyl acetate (1).The compounds were screened as potential H1 receptor agonist on the isolated guinea pig ileum.The 3-halogenated 2-phenylhistamines (halogen = Br (35) and I (36) were equipotent with histamine, while 2-(3-(trifluoromethyl)phenyl)histamine (2-ethanamine (39)) was significantly more potent than histamine (39: pD2 = 6.81, relative activity = 128percent).The 2-substituted histamine analogues were potential H1 receptor agonists on the endothelium-denuded isolated guinea pig aorta with pEC50 values generally smaller than observed on the guinea pig ileum, but the rank order of potency was found to be similar.The contractile effects on guinea pig ileum and aorta, respectively, could be blocked concentraction-dependently by the H1 receptor antagonist mepyramine, yielding KB values for mepyramine in the nanomolar range.In vitro compounds 35 and 39 bound to mepyramine-labeled guinea pig cerebellar membranes with a pKi of 6.1 and 5.9, respectively.However, upon iv administration, 35 (3-100 mg/kg) and 39 (3-300 mg/kg) failed to inhibit the binding of mepyramine to mouse cerebral cortex in vivo , thereby indicating that these histamine derivatives are not able to penetrate the blood-brain berrier.In functional in vitro studies on histamine H2, H3, and other neurotransmitter receptors the selectivity of 39 was found to be 2138 (H1:H2), >64 (H1:H3), 1000 (H1:M3, 105 (H1:α1), 708 (H1:β1) and 71 (H1:5HT2A).Thus compound 39 is the most potent and selective H1 receptor agonist reported so far .These results make meta- substituted 2-phenylhistamines, especially 2-(3-(trifluoromethyl)phenyl)- and 2-(3-bromophenyl)histamine (39 and 35, respectively) valuable experimental tools for the selective stimulation of histamine H1 receptors and the study of H1 receptor-mediated functions.
- Leschke, Christian,Elz, Sigurd,Garbarg, Monique,Schunack, Walter
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p. 1287 - 1294
(2007/10/02)
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- Synthesis of some novel imidate derivatives of thiophene and furan: Investigations of their metallation properties and some synthetic applications
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Methyl N-methyl and methyl N-(2,4,6-trimethyl)phenyl-2-carboximidates of thiophene and furan have been synthesized in excellent yields by the reactions of sodium methoxide in methanol with the corresponding N-methyl- and N-(2,4,6-trimethyl)phenyl-2-carboxymidoyl chlorides, which in turn, were obtained from their respective secondary amides by refluxing in neat thionyl chloride. A thorough investigation into the directed lithiation properties of the these heteroaryl-2-imidates with various lithiating agents, solvents, and reaction conditions revealed almost exclusive C5-lithiation. This regioselectivity is in contrast to the C3-lithiation reported for the oxazolino functionality (a cyclic imidate). The synthetic utility of the C5-lithiated intermediate of methyl N-methyl-thiophene-2-carboximidate with various electrophiles is demonstrated. C3-Lithiation has been effected in the case of methyl N-methylthiophene-2-carboximidate when the C5-position is blocked with a removable trimethylsilyl group. Methyl thiophene-2-carboximidate, an N-unsubstituted imidate, was found to eliminate methoxide ion and undergo subsequent C5-lithiation to give 5-lithiothiophene-2-carbonitrile with LDA. n-Butyllithium gave rise predominantly to products resulting from nucleophilic addition to the nitrile group.
- Barcock, Richard A.,Chadwick, Derek J.,Storr, Richard C.,Fuller, Lance S.,Young, John H.
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p. 4149 - 4166
(2007/10/02)
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