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1.
The cucurbit[6]uril (CB6) host forms stable complexes with 2-aminoethanethiol (cysteamine) and a derivative that contains a bulky terminal group attached to the amine group, as well as with the related disulfide cystamine. In these complexes, the thiol or the disulfide group is encapsulated inside the host cavity. The CB6-complexed thiols show drastically decreased reactivity with several oxidants, while the CB6-bound disulfide also exhibits hindered reactivity with reducing agents, such as dithiothreitol. 相似文献
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Richard D. Adams Burjor Captain Jack L. Smith Jr. 《Journal of organometallic chemistry》2004,689(1):65-70
Diacenaphtho[1,2-c:1′,2′-e]-1,2-dithiin 2 was synthesized in 23% yield by the reaction of acenaphthylene with elemental sulfur at 120 °C. This reaction also afforded either diacenaphtho[1,2-b:1′,2′-d]thiophene 1 or diacenaphtho[1,2-b:1′,2′-e]-dihydro[e]-1,4-dithiin 3 depending on the reaction time. Compound 2 was desulfurized and converted to 1 under UV-vis irradiation in a benzene solution. Reaction of 2 with Pt(COD)2 yielded the complex Pt(COD)(C24H12S2) 4 (COD=1,5-cyclooctadiene) by insertion of a Pt(COD) group into the S-S bond of 2. When heated, 4 was desulfurized and converted to 1 by elimination of a (COD)PtS grouping. Compounds 1-4 were characterized crystallographically. 相似文献
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Klaas Jan van den Berg Steen Ingemann Nico M. M. Nibbering 《Journal of mass spectrometry : JMS》1993,28(5):527-533
The reactions of metal carbonyl anions (M(CO)n?; M = Cr, Mn and Fe; n = 1–3) with n-heptane, water and methanol were studied with use of a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with an external ion source. The M(CO)n? ions were formed in the FT-ICR cell by collision-induced dissociation of the most abundant primary ion generated by electron impact of the appropriate metal carbonyl compound present in the external ion source. The M(CO)n? ions were allowed subsequently to undergo non-reactive collisions with argon in order to remove possible excess internal/translational energy prior to the ion/molecule reaction. Only the Cr(CO)3?, Mn(CO)3? and Fe(CO)2? ions react with n-heptane. This reaction proceeds by loss of H2 from the collision complex and the Cr(CO)3? and Fe(CO)2? ions react about three times more efficiently than the Mn(CO)3? ion. With water, Mn(CO)? and Fe(CO)3? are unreactive, whereas the other ions react by loss of one or two CO molecules from the collision complex. The rate of the reaction with water decreases in the order Cr(CO)3?, Fe(CO)2?, Cr(CO)2?, Fe(CO)?, Mn(CO)3? and Mn(CO)2?. With methanol, the Cr(CO)2? ion reacts by loss of two CO molecules from the collision complex, whereas loss of one CO molecule and elimination of CO + H2 occur in the reaction with Cr(CO)3?. Competing loss of CO and one or two H2 molecules occurs in the reactions of Mn(CO)3? and Fe(CO)2? with methanol. The rate of the reaction with methanol decreases in the order Cr(CO)3?, Fe(CO)2?, Cr(CO)2? and Mn(CO)3?. 相似文献
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Frantisek Povazanc Bernard Decroix Jean Morel 《Journal of heterocyclic chemistry》1992,29(6):1507-1512
A convenient method for the synthesis of furo[2,3-e]pyrrolo[1,2-a][1,4]diazepin-9-one is described. It has been C-alkylated with amine (piperidine, morpholine, 4-methylpiperazine) and N-alkylated with alkyl halides (methyl iodide and benzyl chloride). 相似文献
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The reactions of benzimidazo[1,2-c][1,2,3]benzotriazine (1) with fluoroboric acid, potassium iodide and phenyl isothiocyanate are described. The structure of the phenyl isothiocyanate product is elucidated by chemical and spectroscopic techniques. The reaction of 1 with alcoholic potassium hydroxide is shown to proceed by a free radical mechanism. The structure of the compound formed from 1 and sodium diethyl malonate is investigated by spectroscopic methods. The reduction and photochemical reactivity of 1 are also discussed. 相似文献
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Alain Gueiffier Henri Viols Yves Blache Jean Pierre Chapat Olivier Chavignon Jean Claude Teulade Florence Fauvelle Grard Grassy Grard Dauphin 《Journal of heterocyclic chemistry》1997,34(3):765-771
The synthesis and reactivity of imidazo[1,2-a][1,8]naphthyridines are reported. Electrophilic substitution reactions were studied and the site of the reaction was established with the aid of high-field 1H and 13C nmr spectra. The experimental C-1 position reaction was correlated with a CNDO/2 calculations. 相似文献
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S. A. Grabovskii E. A. Markov E. G. Galkin N. N. Kabal’nova 《Kinetics and Catalysis》2009,50(2):180-185
The products and kinetics of the thermolysis of 1,2-dioxaspiro[2,5]octane in cyclohexanone and cyclohexanone-CCl4 mixtures are studied. 1,2-Dioxaspiro[2,5]octane is consumed via two parallel routes: isomerization to oxepan-2-one and solvent (cyclohexanone) oxidation with the partial escape of radicals from the cage (17% at 25 °C). Under an inert atmosphere, the alkyl radicals formed by solvent oxidation initiate the chain radical decomposition of 1,2-dioxaspiro[2,5]octane. The mechanism of 1,2-dioxaspiro[2,5]octane thermolysis is discussed on the basis of the results obtained. The activation parameters of 1,2-dioxaspiro[2,5]octane isomerization to oxepan-2-one and reactions of dioxaspiro[2,5]octane with cyclohexanone are discussed. 相似文献
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A. W. Castleman Jr. A. C. Harms R. E. Leuchtner 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,19(4):343-346
Reaction kinetics of metal cluster ions under well defined thermal conditions were studied using a flow tube reactor in combination with laser vaporization. Aluminum anions and cations were reacted with oxygen, and several species which are predicted jellium shell closings, were found to have special stability. Metal alloy cluster anions comprised of Al, V and Nb were also seen to react with oxygen. Alloy clusters with an even number of electrons reacted more slowly than odd electron species, and certain clusters appeared to be exceptionally unreactive. Copper cation clusters were observed to associate with carbon monoxide with reactivities that approach bulk behavior at surprisingly small cluster size. These reactions demonstrate how the rate of reaction changes with cluster size. 相似文献
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Peter Uebelhart Peter Mohler Reza-Ali Fallahpour Hans-Jürgen Hansen 《Helvetica chimica acta》1995,78(6):1437-1464
The dehydrogenation reaction of the heptalene-4,5-dimethanols 4a and 4d , which do not undergo the double-bond-shift (DBS) process at ambient temperature, with basic MnO2 in CH2Cl2 at room temperature, leads to the formation of the corresponding heptaleno[1,2-c]furans 6a and 6d , respectively, as well as to the corresponding heptaleno[1,2-c]furan-3-ones 7a and 7d , respectively (cf. Scheme 2 and 8). The formation of both product types necessarily involves a DBS process (cf. Scheme 7). The dehydrogenation reaction of the DBS isomer of 4a , i.e., 5a , with MnO2 in CH2Cl2 at room temperature results, in addition to 6a and 7a , in the formation of the heptaleno[1,2-c]-furan-1-one 8a and, in small amounts, of the heptalene-4,5-dicarbaldehyde 9a (cf. Scheme 3). The benzo[a]heptalene-6,7-dimethanol 4c with a fixed position of the C?C bonds of the heptalene skeleton, on dehydrogenation with MnO2 in CH2Cl2, gives only the corresponding furanone 11b (Scheme 4). By [2H2]-labelling of the methanol function at C(7), it could be shown that the furanone formation takes place at the stage of the corresponding lactol [3-2H2]- 15b (cf. Scheme 6). Heptalene-1,2-dimethanols 4c and 4e , which are, at room temperature, in thermal equilibrium with their corresponding DBS forms 5c and 5e , respectively, are dehydrogenated by MnO2 in CH2Cl2 to give the corresponding heptaleno[1,2-c]furans 6c and 6e as well as the heptaleno[1,2-c]furan-3-ones 7c and 7e and, again, in small amounts, the heptaleno[1,2-c]furan-1-ones 8c and 8e , respectively (cf. Scheme 8). Therefore, it seems that the heptalene-1,2-dimethanols are responsible for the formation of the furan-1-ones (cf. Scheme 7). The methylenation of the furan-3-ones 7a and 7e with Tebbe's reagent leads to the formation of the 3-methyl-substituted heptaleno[1,2-c]furans 23a and 23e , respectively (cf. Scheme 9). The heptaleno[1,2-c]furans 6a, 6d , and 23a can be resolved into their antipodes on a Chiralcel OD column. The (P)-configuration is assigned to the heptaleno[1,2-c]furans showing a negative Cotton effect at ca. 320 nm in the CD spectrum in hexane (cf. Figs. 3–5 as well as Table 7). The (P)-configuration of (–)- 6a is correlated with the established (P)-configuration of the dimethanol (–)- 5a via dehydrogenation with MnO2. The degree of twisting of the heptalene skeleton of 6 and 23 is determined by the Me-substitution pattern (cf. Table 9). The larger the heptalene gauche torsion angles are, the more hypsochromically shifted is the heptalene absorption band above 300 nm (cf. Table 7 and 8, as well as Figs. 6–9). 相似文献
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The synthesis of isoindolo[2,1-b]pyrrolo[1,2-d][2,4]benzodiazocine 7 and isoindolo[1,2-d]pyrrolo[1,2-a]-[1,5]benzodiazocine 13 are described starting from 2-(2-methoxycarbonyl)benzylphthalimide 1a and ethyl α-bromohomophthalate 9 respectively. 相似文献
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Pasynskii A. A. Dobrokhotova Zh. V. Torubaev Yu. V. Semenova N. I. Novotortsev V. M. 《Russian Chemical Bulletin》2003,52(1):109-115
The thermal decay of 19 individual carbonyl homo- and heterochalcogenide clusters with different M/X ratios (M = Fe, Mn, Pt, Cr, W, Mo, Re, Ru; X = S, Se, Te) was studied by differential scanning calorimetry and thermogravimetry. The process is stepwise and occurs at relatively low temperatures (100—350 °C). The general fact of incomplete removal of carbon monoxide (due to the formation of carbide and oxide impurities) during thermolysis of narbonyl chalcogenide clusters with the M : X ratio greater than 1 was elucidated. Conversely, when M : X 1 (or at any M/X ratio for clusters containing methylcyclopentadienyl groups), pure metal chalcogenides are formed. 相似文献
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Hussein El-Kashef Sylvain Rault Jean-Charles Lancelot Max Robba 《Journal of heterocyclic chemistry》1986,23(1):161-167
The synthesis of several [1]benzothieno[2,3-e]pyrrolo[1,2-a]pyrazines and other related heterocycles has been described. A study of the nmr spectra of these compounds was also reported. 相似文献
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Hydrazonoyl bromides 1a-c react with 5-amino-3-phenyl-1H-pyrazole, 5-amino-1H-1,2,4-triazole, 2-aminopyridine, and 2-aminobenzimidazole to afford the corresponding imidazol[1,2-b]pyrazoles 10, imidazo[1,2-b]-1,2,4-triazoles 11, imidazo[1,2-a]pyridines 16, imidazo[1,2-a]pyrimidines 17, and imidazo[1,2-a]benzimidazoles 20, respectively. Compounds 1a-c reacted also with 2-methylthiobenzimidazole to give 1,2,4-triazolo[4,3-a]benzimidazole derivatives 21. © 1997 John Wiley & Sons, Inc. 相似文献