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11.
Aparicio D Attanasi OA Filippone P Ignacio R Lillini S Mantellini F Palacios F de Los Santos JM 《The Journal of organic chemistry》2006,71(16):5897-5905
The preparation of tetrahydropyrazines, dihydropyrazines, pyrazines, piperazinones, and quinoxalines by 1,4-addition of 1,2-diamines to 1,2-diaza-1,3-butadienes bearing carboxylate, carboxamide, or phosphorylated groups at the terminal carbon and subsequent internal heterocyclization is described. The solvent-free reaction of carboxylated 1,2-diaza-1,3-butadienes with the same reagents affords piperazinones, while phosphorylated 1,2-diaza-1,3-butadienes yield phosphorylated pyrazines. The solid-phase reaction of polymer-bound 1,2-diaza-1,3-butadienes with 1,2-diamines produces pyrazines. 相似文献
12.
L. S. Lussier C. Sandorfy H. OA L E-Thanh D. Vocelle 《Photochemistry and photobiology》1987,45(S1):801-808
Abstract— The Fourier-transform infrared spectra of chloroform-d solutions of conjugated imines CH3 CH=CHCH=NCH(CH3 )2 and CH3 CH2 CH=CHCH=CHCH=NCH(CH3 )2 and the related protonated species with HCl, HBr, HI, trichloro, dichloro, monobromo and monochloroacetic acids or propionic acid are presented. The effects of conjugation and protonation are examined. The results show that conjugation slightly increases the basicity of the Schiff bases. HCl, HBr and HI protonate the Schiff bases completely. The carboxylic acids protonate partially depending on their p K a , values. When the Schiff base contains two (or more) C=C bonds conjugated with C=N, the main C=C stretching band undergoes a strong intensification showing that sizeable dipole moment variations occur along the conjugated chain. 相似文献
13.
Giorgi G Salvini L Attanasi OA Guidi B Santeusanio S 《Journal of mass spectrometry : JMS》2002,37(2):169-178
Electron ionisation mass spectrometry was usefully used to characterize structurally 2-aryl-5-acetylthiazole derivatives in the gas phase. The compounds show characteristic fragmentation pathways depending on the chemical nature of the substituent at position 2, consisting mainly in the cleavage of both the 1,2- and 3,4-bonds of the thiazole ring. Liquid secondary ion mass spectrometry was applied to study the effects of protonation on the gas-phase unimolecular reactions of this class of compound. Tandem mass spectrometric experiments, carried out on molecular and protonated molecular ions, and also on fragment ions produced in the source, allowed the elucidation of gas-phase decompositions of low-internal energy ions. 相似文献
14.
Attanasi OA Baccolini G Boga C De Crescentini L Filippone P Mantellini F 《The Journal of organic chemistry》2005,70(10):4033-4037
[structures: see text] The present article describes the reaction between 1,2-diaza-1,3-butadienes and trialkyl phosphites, under an atmosphere of nitrogen and under solvent-free conditions, to give alkyl 3,3-dialkoxy-2H-1,2,3lambda5-diazaphosphole-4-carboxylates that, in turn, are converted into corresponding E-hydrazonophosphonates by treatment with THF:water (95:5). These latter compounds are obtained directly by the reaction of 1,2-diaza-1,3-butadienes with trialkyl phosphites in the presence of air. These compounds are useful for the further preparation of dialkyl (5-methyl-3-oxo-2,3-dihydro-1H-4-pyrazolyl)phosphonates and 2-dialkoxyphosphoryl-1,2,3-thiadiazoles. 相似文献
15.
In the course of our previous investigations, we dealt with the direct synthesis of unknown 1-aminopyrroie derivatives, obtained by reaction of some azoalkenes with B-diketones, 8- ketoesters, or B-ketoamides under copper (II) ionscatalysis. 1-9 相似文献
16.
Orazio A. Attanasi Paolino Filippone Fabio Mantellini Jesús M. de los Santos Domitila Aparicio 《Tetrahedron》2008,64(39):9264-9274
The synthesis of substituted 2,3-dihydro-1,4-thiazines, fused cycloalkyl-1,4-thiazines, 1,4-benzothiazines and fused cycloalkyl-1,4-benzothiazines by 1,4-addition of 1,2-aminothiols to 1,2-diaza-1,3-dienes bearing carboxylate, carboxamide, or phosphorylated groups and subsequent internal heterocyclization is described. The reaction of carboxylated 1,2-diaza-1,3-butadienes with 2-(butylamino)ethanethiol affords 1,4-thiazinan-3-ones. The solid-phase reaction of polymer-bound 1,2-diaza-1,3-butadienes with 1,2-aminothiols produces 2,3-dihydro-1,4-thiazines and 1,4-benzothiazines. 相似文献
17.
A supercooled liquid is said to have a kinetic spinodal if a temperature Tsp exists below which the liquid relaxation time exceeds the crystal nucleation time. We revisit classical nucleation theory taking into account the viscoelastic response of the liquid to the formation of crystal nuclei and find that the kinetic spinodal is strongly influenced by elastic effects. We introduce a dimensionless parameter lambda, which is essentially the ratio between the infinite frequency shear modulus and the enthalpy of fusion of the crystal. In systems where lambda is larger than a critical value lambda(c) the metastability limit is totally suppressed, independently of the surface tension. On the other hand, if lambda相似文献
18.
19.
Orazio A. Attanasi Lucia De Crescentini Paolino Filippone Samuele Lillini 《Tetrahedron letters》2007,48(14):2449-2451
New tetrahydro-3aH-cyclopenta[d][1,3]thiazolines and hexahydro-1,3-benzothiazolines were obtained in satisfactory yields by reaction of cycloalkenyl-1-diazenes with thioamides. These thiazolines were converted into unknown fused cycloalkyl-thiazoline-pyrazole systems. 相似文献
20.
Orazio Attanasi Giuseppe Bartoli Paolo E. Todesco 《Journal of heterocyclic chemistry》1976,13(5):1021-1024
The rates of base-catalyzed hydrogen-deuterium exchange at C-2 in some 6-substituted benzothiazoles were studied and compared with the analogous values pertinent to some 5-substituted benzothiazoles, reported in a previous paper. The simple Hammett equation was found not to allow a good interpretation of the experimental data. However, a good agreement was obtained by the application of the Hammett-Jaffé equations. From these calculations, it was concluded that the sulphur and the nitrogen heteroatoms of the thiazole ring have, in these reactions, a very similar activity in the transmission of the substituent effects from the benzo ring at C-2 of the thiazole ring. Therefore, while in other reactions only the nitrogen heteroatom is active, in these reactions a considerable stabilization of the α-carbanion is clearly shown also by the sulphur heteroatom. 相似文献