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3-Nitro-1,5-naphthyridine and its 2-substituted derivatives (1a-f) are dehydro-methy laminated with a solution of potassium permanganate in liquid methylamine (LMA-PP) to the corresponding 4-methylamino-3-nitro-1,5-naphthyridines ...
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3-Nitro-1,5-naphthyridine and its 2-substituted derivatives (1a-f) are dehydro-methy laminated with a solution of potassium permanganate in liquid methylamine (LMA-PP) to the corresponding 4-methylamino-3-nitro-1,5-naphthyridines (3a-e). The intermediary 4-methylamino sigma adducts of 2-R-3-nitro-1,5-naphthyridines (R = H, NH2, Cl, NHCH3, OC2H5, OH) (2a-f) are detected by H-1 nmr spectroscopy. The observed highly regioselective course of study reactions was confirmed by PM3 quantum chemical calculations of the reaction pathway. The calculations show satisfactory agreement between calculated and observed results. A convenient synthesis of 2-hydroxy- and 4-methylamino-3-nitro-1,5-naphthyridine are reported.
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A simple method for the preparation of 1,7-naphthyridine and 1,6-naphthyridine from the corresponding aminopyridine starting materials is presented.
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Drugs acting on beta(1)- and beta(2)-adrenergic receptors are widely used for the clinical management of a large number of cardiovascular and respiratory pathologies. In the last decade, the discovery of the third subtype of beta ...
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Drugs acting on beta(1)- and beta(2)-adrenergic receptors are widely used for the clinical management of a large number of cardiovascular and respiratory pathologies. In the last decade, the discovery of the third subtype of beta receptors, the beta(3)-adrenoceptor, gave a further pharmacological target for the development of new selective drugs. Initially, a potential therapeutic use of beta(3)-selective agents seemed to be restricted to agonists, for the treatment of metabolic diseases, such as obesity, non-insulin-dependent diabetes, urinary frequency and incontinence. More recently, some interesting theories about a negative role played by the cardio-depressant activity of myocardial beta(3)-adrenoceptors in heart failure, seemed to justify a clinical use of beta(3)-antagonists in the last phases of this cardiac disease. Following the indications deriving from previous experimental work, the beta-antagonist properties of newly-synthesised (R,S)-(E)-oximeethers of 2,3-dihydro-1,8-naphthyridine and of 2,3-dihydrothiopyrano[2,3-b]pyridine were evaluated, in order to identify some useful structure-activity relationships, which might account for selectivity towards the three beta-subtypes and, in particular, the beta(3)-adrenoceptor. Among the various observations regarding possible structure-activity relationships, able to explain the pharmacodynamic patterns of the synthesised compounds on the three subtypes of beta-adrenoceptors, the most significant data derived from the evaluation of the beta(3)-blocking properties of some oximeethers of 1,8-naphthyridine derivatives. In these molecules, although the presence of the large substituents in position 7, such as 4-chloro-phenoxy- or 4-t-butyl-phenoxy groups determined a dramatic decline in both the beta(1)- and beta(2)-activities, this structural characteristic had a modest influence on the beta(3)-affinity, which was only slightly lower. Hence, this last structural requirement of oximeethers of 1,8-naphthyridine derivatives seems to represent a useful expedient to induce an appreciable selectivity towards the beta(3)-receptor, through a markedly negative effect on the beta(1)- and beta(2)-activities rather than an increase in the beta(3)-affinity.
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The title compound, C(24)H(19)N(3)O, crystallizes in the centrosymmetric space group P2(1)/a with one molecule in the asymmetric unit. The tetrahydropyridine ring has a boat conformation. The dihedral angle between the fused pyrid...
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The title compound, C(24)H(19)N(3)O, crystallizes in the centrosymmetric space group P2(1)/a with one molecule in the asymmetric unit. The tetrahydropyridine ring has a boat conformation. The dihedral angle between the fused pyridine rings is 16.2 (1) degrees. The equatorial and axial orientations of the two phenyl groups with respect to the tetrahydropyridine ring are confirmed. The nitroso group is coplanar with the attached C-N-C group. The interplanar angle formed between the fused tetrahydropyridine and benzene planes is 13.4 (1) degrees. The crystal packing is stabilized by an intermolecular C-H.O hydrogen bond, which forms a C(9) graph-set chain running along the [001] direction.
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Several 1,8-naphthyridine derivatives have been diazotizated to obtain the corresponding hydroxy derivatives or mixture of hydroxy and hydroxy nitro derivatives. The respective amounts of hydroxy and hydroxy nitro derivatives depe...
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Several 1,8-naphthyridine derivatives have been diazotizated to obtain the corresponding hydroxy derivatives or mixture of hydroxy and hydroxy nitro derivatives. The respective amounts of hydroxy and hydroxy nitro derivatives depends on the nature of the substituents, on their position on the naphthyridine nucleus, on the amount of sodium nitrite and on the reaction temperature. A study of the electronic density of some molecules suggests a possible explanation of the effects induced by the nature of the substituents and of their position. Some of the compounds were tested for their ability to inhibit human platelet aggregation in vitro induced by arachidonic acid. Only compound 26 showed interesting antiplatelet activity. [References: 26]
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Reaction of substituted 2-aminopyridines with diethylmalonates yields 2,4-dihydroxy-1,8-Naphthyridenes(1-18). The 6-chloro-2,4-dihydroxy-1,8- naphthyridene (5) when treated with different reagents varied substituted derivatives ar...
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Reaction of substituted 2-aminopyridines with diethylmalonates yields 2,4-dihydroxy-1,8-Naphthyridenes(1-18). The 6-chloro-2,4-dihydroxy-1,8- naphthyridene (5) when treated with different reagents varied substituted derivatives are produced. 6-chloro-2, 4-dihydroxy-1,8-naphthyridene(5) when treated with sodium azide offered 2,4- dihydroxy-1,8-naphthyridene-6-thiones (19-21). 6-azido-1,8-naphthyridine-2,4- diols(22-24) were obtained by reacting 5 with sodiumazide. The 6-hydraziny1-1,8-naphthyridine-2,4-diols (25-27) and 2,4,6-trihydroxy-1,8-naphthyridenes (28-30)were produced by the reaction of 5 with hydrazine hydrate and acetic acid respectively.
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The new and efficient synthesis of the title heterocyclic ring system is described starting from suitable 2-chloro-1, 8-naphthyridines. The synthesized 6H-indolo[2, 3-b][1, 8]naphthyridine derivatives were tested in vitro on 55 tu...
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The new and efficient synthesis of the title heterocyclic ring system is described starting from suitable 2-chloro-1, 8-naphthyridines. The synthesized 6H-indolo[2, 3-b][1, 8]naphthyridine derivatives were tested in vitro on 55 tumor cell lines for their anticancer properties. The presence of the acetylamino moiety at position 3 in the main ring system proved to be crucial for the cytostatic activity of this class of compounds.
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A dually activated ketene enolate, generated from an acid chloride, the unusual chelating nucleophile (1,8- naphthyridine), and a Lewis acid, reacts to afford a host of α,α-difluorinated products in the presence of a benchtop-st...
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A dually activated ketene enolate, generated from an acid chloride, the unusual chelating nucleophile (1,8- naphthyridine), and a Lewis acid, reacts to afford a host of α,α-difluorinated products in the presence of a benchtop-stable fluorinating agent (Selectfluor). The use of this method to synthesize otherwise difficult to make products is highlighted along with computational and spectroscopic support for the proposed chelate.
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2-Chlorobenzo[b][1,8]naphthyridines 4a-f are synthesised in good yields utilizing 3-(2-chloro-3-quinolyl)acrylic acids 2a-f as the starting compounds.
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The reaction of 2-nitrobenzaldehyde with methyl propiolate and ammonium acetate in acetic acid yields 2,6-dinor-nifedipine (1a) and as a by-product not the dimethyl 2,5-dicarboxylate isomer, but the rac. 1,2-dihydropyridine (DHP) ...
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The reaction of 2-nitrobenzaldehyde with methyl propiolate and ammonium acetate in acetic acid yields 2,6-dinor-nifedipine (1a) and as a by-product not the dimethyl 2,5-dicarboxylate isomer, but the rac. 1,2-dihydropyridine (DHP) 1b, as proven by X-ray analysis. The benzo[h][1,6]naphthyridines 4-6 are synthesized from the oxidation product 2b and the photo-product 3b. The compounds 6 represent starting materials for potential anti-malarial agents.
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