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1.
Starting from 2-bromo-5-methoxyacetophenone, an unambiguous synthesis of the selenium analog of serotonine is described with a 25% overall yield. Application of the Wittig reaction to selenoindoxyls appears to be a successful pathway to products of this nature.  相似文献   

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Some furochromenes substituted at the 2-position by an electron-attracting group were obtained starting from ortho-hydroxyformyl derivatives of 2,2-dimethyl-2H-chromene following various processes which are indicated. These new furochromenes are pharmacochemical analogues of some natural pyranocoumarins, and as such they are potential photosensitizers.  相似文献   

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Nucleophilic aromatic substitution of 3-bromo-2nitrothiophene and selenophene by thiocyanate and selenocyanate ions in dimethylsulfoxide yields 3-thienyl-and 3-selenienylthicoyanates and selenocyanates. After reduction of the nitro group, the amino derivatives undergo cyclizatrion to thieno[2,3-d]thiazoles and seleno [2,3-d]thiazoles. Also, 4H-2,3-dihydro-3-oxothieno[2,3-e]1,4-thiazine and its selenophene analog have been obtained.  相似文献   

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The Neber rearrangement applied to the oxime tosylates of the 4- and 3-tetrahydropyranones gives the α-aminoacetals 5 and 20 , as well as 3-amino-4,4-diethoxy and 2-amino-3,3-diethoxy-tetrahydropyranes. The hydrolysis of the former gives the pyrazine 6 and the latter gives the aminoketone 21. On the other hand the aminoacetal 5 allows one to obtain the 4-acetoxy-3-trimethylammonium tetrahydropyran iodide ( 12 ) with a preferential cis axial acetoxy equatorial trimethylammonium conformation. The oxime tosylate of the 3-tetrahydropyranone readily undergoes the Beckman rearrangement into lactam 18 whose open chain product is the (3-aminopropoxy)acetic acid ( 19 ).  相似文献   

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We describe the first synthesis of 2-arylbenzo[4,5]thieno-[2,3-b]pyran-4-one and of 2-arylbenzo [4,5] thieno [3,2-b] pyran-4-one, from benzo [4,5] thiophene and we have extended these cyclizations to obtain the heterocyclic analogs of the xanthones.  相似文献   

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The results of nucleophilic substitution of the 2-methoxy-9-acridone are discussed in terms of competition between both ionic sites N? and O?, of the molecule. They are the first examples of O-alkylation of substituted 9-acridone.  相似文献   

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Proton and carbon magnetic resonance spectra of mono-and disubstituted selenophenes are investigated. The proton chemical shifts are discussed in terms of magnetic anisotropy and electric field effects of the substituents, with a view to studying the conformational equilibrium of the carbonyl group. π Electronic charges, computed by the PPP method, are correlated with the proton and carbon chemical shifts. The coupling constants between 13C and 1H (1, 2 or 3 bonds) and 13C? 77Se are shown to be good structural parameters and a set of substituent additivity constants is calculated.  相似文献   

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The alkylation of Δ4-thiazoline-2-thiones under phase transfer catalysis conditions leads to the corresponding thioethers in good yields. The oxidation of 2-alkylthiazoles with m-chloroperbenzoic acid leads to the corresponding sulfines or sulfones depending on experimental conditions in yields of about 80-90%. The characteristic gle, tlc, ir, 1H nmr and ms data are reported for most of the compounds studied.  相似文献   

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By a judicious choice of the fusion reaction parameters, mainly the percentage of catalyst, we have obtained the corresponding benzotriazole and benzimidazole nucleosides substituted at N-2. We have also obtained the α N-1 anomers. Thus, we have shown it is possible, to confer some selectivity to the acid-catalyzed fusion-reaction.  相似文献   

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A six step synthesis of 4,5-dihydroimidazo[4,5,I-ij]quinolin-6-one type from o-nitraniline is described. The final 6-keto group on the reduced pyridine moiety allows the introduction of various substituents.  相似文献   

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Several mono-, di-, and tri-hydroxy derivatives of cyclopentane and cyclopentene have been studied by NMR. spectroscopy. The chemical shifts and the coupling constants of the OH groups have been correlated with their position, with their configuration and, in some cases, with their conformation.  相似文献   

17.
Two as yet unknown cyclopentene-triols have been prepared. The replacement of the halogen of cyclopentene derivatives brominated in the allylic position has been investigated. In the presence of dimethyl sulfoxide and sodium hydrogen carbonate, the bromine of some of the above mentioned allylic derivatives or the tosyloxy group of a dibenzoyloxy-monotosyloxy-cyclopentane derivative is replaced by a hydroxyl group without formation of any keto compound. The mechanism of action of the substitution agents is discussed.  相似文献   

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The conversion to free ketoses by transketalisation of ethylene-ketal and/or isopropylidene derivatives of polyhydroxy-cyclopentanones has been investigated. The preparation of 2, 3-dihydroxy-cyclopentanone and of 2, 3-dihydroxy-cyclopentenone has been described.  相似文献   

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