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1.
Carbohydrate Derivatives Bearing a gem-Dihalogenoethenyl Group Treated with the appropriate Wittig reagent, aldehydosugar derivatives ( 1–13 ) led in good to excellent yields to the expected gem-difluoro, gem-chlorofluoro-and/or gem-dichloroenoses ( 14–29 ). Examples of their dibromo analogues had been previously described (see e.g. [1]) but the diiodo derivatives could not be isolated, The influence of the conditions on the yields is reported as well as spectroscopic properties (particularly the long-range 13C, 19F- and 1H, 19F-coupling constants) of these new enoses. 相似文献
2.
Deconjugation of sugars enones. Preliminary Communication Branched-chain sugar enones 1 and 2 ( R = Ac) deconjugated toposelectively (only the E isomers reacting) to 3 . The same phenomenon was noted in the case of Z- 4 which gave E- 5 . The kinetic parameters of these reactions favored a concerted mechanism, i.e. a [1, 5]-sigmatropic shift. 相似文献
3.
We herein descirbe various methods for synthesizing 1-foryml-2-hydroxyanthracene, 2-formyl-1-hydroxyanthracene and 1-formyl-2-hydroxy 6-methoxyanthracene. These compounds are used as starting materials to prepare anthrafuran derivates nitracted on their heterocycles in order to copare their mutagenic properties to that of the corresponding nitro-derivates of naphthofurans. 相似文献
4.
By condensation of the chlorides of the four isomeric fluorenecarboxylic acids, respectively of the three 1-, 3- and 4-fluorenonecarboxylic acids with fluorene, followed by reduction of the obtained mono-respectively diketones, the four difluorenylmethanes I, II, III and IV are synthesized. The oxydation of the diketones gives the corresponding triketones. Starting from the chloride of 4-fluorenecarboxylic acid and 1-methylfluorene, a methyl derivative of IV is analogically obtained. 相似文献
5.
A. Merbach 《Helvetica chimica acta》1967,50(5):1431-1435
In a solution containing an excess of two metal ions in regard to a ligand (e.g. NTA) a competitive equilibrium is established. The measure, by proton NMR. spectroscopy, of the individual concentrations of both chelates, and eventually of the free ligand, allows to determine the ratio of the stability constants of the two complexes. As an illustration the ratios of the stability constant of the 1:1 nitrilotriacetate chelates of Pb and Zn, respectively Mo and W, were determined. 相似文献
6.
Joëlle Mayrargue Michel Duchon D'Engenires Marcel Miocque 《Journal of heterocyclic chemistry》1978,15(2):263-267
By cyclization in aqueous media, 2-aminomethyl 1-alcynyl 1-cyclohexanols lead to perhydroisoindolinium or perhydroisoquinolinium salts. The stereochemistry of isolated diastereoisomers is elucidated. A stereoselectivity favouring trans junction of the rings is pointed out. 相似文献
7.
In this paper, we describe the results of a study of the reaction of diaryl nitrilimines with N-ethylindole ( 1 ) and 2-methoxycarbonyl-N-ethylindole ( 2 ). The regioselectiivity of the reaction is reversed when going from 1 to 2 as it has been spectroscopically and chemically demonstrated. 相似文献
8.
Jean-Marie Costnao Noul Collision Gay Quaguiner 《Journal of heterocyclic chemistry》1979,16(5):973-976
The reduction-aldylation of quinoxaline, phthalazine and pyrido[2,3-b] pyrazine by potassium borohydride in a carboxylic acid medium is described. Formic, acetic, chloroacetic and propinic acids were used. The diazine ring of the molecule was reduced and alkylated into an N,N1-dialkyltetrahydro compound. With quinoxaline and formic acid, N-formylation may be an important factor. Sodium borodeuteride allows one to prepare an hexadeuterated compound. 相似文献
9.
Free radical addition of tetrahydrofuran and tetrahydropyran to various allenes gives mainly 1:1 adducts. Increasing substitution on the allenic triad involves a change in ratio of adduct formed by way of central attack (1% with propadiene, 99% with 2,4-dimethyl-2,3-pentadiene). 相似文献
10.
El Mostafa Tjiou Alain Fruchier Valdo Pllegrin Georges Tarrago 《Journal of heterocyclic chemistry》1989,26(4):893-898
The pKa1 and pKa2 of 19 biheterocycles A-(CH2)-n B(in which A and B represent pyrazole, imidazole, or pyridine rings, and n=0 or 1) were determined in water at 25° using poterntiometry and UV spectroscopy methods. 相似文献
11.
The mass spectrometric study of a series of enolic phosphates of type A leades to fragmentation patterns influenced by the nature of the substituents (R, R′ and R″). It is generally observed that a simple or double hydrogen rearrangement occurs with the loss of the enolic groups. When R and R′ are alkyl groups, the migrating groups are the hydrogen atoms on the alkyl group at position 1. When there is no alkyl group at position 1, the hydrogen atoms of the alkyl group at position 2 induce the rearrangement process. Finally, if R, R′ and R″ are hydrogen atoms, the loss of the enolic chain occurs without any rearrangement. 相似文献
12.
Yvonne Gelas-Mialhe Rolland Hierle Roger Vessire 《Journal of heterocyclic chemistry》1974,11(3):347-349
1-Alkyl-2-(N-methylidenealkylamino)aziridines are obtained by the reaction of primary amines with either α-chloroacraldehyde or α-chlorocrotonaldehyde. Structural assignments are made by nmr spectroscopy. The thermal rearrangement of 1-alkyl-2-(N-methylidenealkylamino)-3-methylaziridines to pyrroles is described. 相似文献
13.
Colette Deschamps-Vallet Michle Meyer-Dayan Jean Andrieux Jacques Riboulleau Bernard Bodo Darius Molho 《Journal of heterocyclic chemistry》1977,14(3):489-492
5-Oxo-5H,7H-[2]benzopyrano[4,3-b][1]benzopyran ( 2 ) has been synthesized from 3-(o-hydroxybenzylidene)isochroman-1,4-dione ( 3 ) by reductive cyclization, and from 5H,7H[2]benzo-pyrano[4,3-b][1]benzopyran-5,7-dione ( 4 ) by selective hydro-genation. This second method affords the dihydro compound 6 or 6a,12a-dihydro-5H,7H-[2]benzopyrano[4,3-b] [1 ]benzopyran-5-one as reaction time increases. 相似文献
14.
J. Ploquin L. Sparfel G. Le Baut R. Floc'h Et Y. Letourneux 《Journal of heterocyclic chemistry》1980,17(5):961-973
The condensation of methylated N-heterocycles and espically monomethyl- and polymethylpyridinets on phthalic enhydrides leads to 2-ary1-1,3-indanediones. The 3alklidenylphthalides formed in an intermediary state have been isloated. The influence of solvents and temperature on the velocity and yeild of formation of 2-(2- and 4-pyridyl)-1,3-indandiobnes has been studies. The ir and nmr spectra confirm taht these compunds exist under a β-diketoenamine form resonating witj a betaine form. 相似文献
15.
Jean-Marie Webert Denise Cagniant Paul Cagniant Gilbert Kirsch Jean-Victor Weber 《Journal of heterocyclic chemistry》1983,20(1):61-64
The influence of annelaction and of the heteroatom upon the reactity of some haterocyclic analogus of phenanthrene with a pyrrole nucleos was tested toward acetylation and lithiation. If methy-l[1]benzofuro-[3,2-b]pyrrole was acetylated only in the 2-position, the sulfer and selenious analogues with [3,2-b] and [2,3-b] annelarion were acetylated in the -2 and -3 position. No reaction at all or only with poor yield (in the oxygenated series) was observed with butyllithium except on the case of l-methyl[1]benzoselenono[2,3-b]pyrrole, where the opening of the selenophene nucleos gives, after carbonation and action of diazomethane, l-methyl-2-methoxycarbony 1-3-(o-methylselenophenyl) pyrrole. 相似文献
16.
The derivative C13H19NO5 crystallizes in space group P212121 with a = 9.371, b = 11.815, c = 13.207 Å and Z = 4. The structure was solved by direct methods and refined by full-matrix least-squares to R = 0.058. The pyranose ring exists in the 3S1 conformation (or in the equivalent, but here structurally less consistent, 0S4 conformation). The dioxolane ring has an envelope conformation. Strong intramolecular interactions between the bulky substituents suggest that the ensuing strain energy is assumed, for a significant part, by the twisted-boat conformation of the pyranose ring. 相似文献
17.
Jean M. J. Tronchet Alain P. Bonenfant Kemal Deen Pallie Ford Habashi 《Helvetica chimica acta》1979,62(5):1622-1625
Derivatives of enose- and ynosephosphonates and related compounds. Preliminary communication The gem-dibromo terminal enoses 1 and 7 are convenient sources of glycosylacetylenes which upon reaction with phosphorus electrophiles gave the phosphorusbearing acetylenic sugars 4, 5 and 8 . Compounds 5 and 8 underwent cycloaddition reactions leading to isoxazolyl-C-glycosides 6 and 9 respectively. The nitroolefinic sugar derivative 11 gave upon bromination-dehydrobromination the first example of a new kind of potentially useful synthetic intermediates, the gem-bromonitroenose 12 . The enosephosphonate 13 was also prepared from 11 . The diglycosylhydroxylamine 18 represents another type of phosphorus-bearing acetylenic sugar derivative. Some 1H- and 13C-NMR. data relative to the new types of phosphorus-containing sugar derivatives synthesized are given. 相似文献
18.
C. Gey R. Perraud J. L. Pierre H. Cousse L. Dussourd D'Hinterland G. Mouzin 《Magnetic resonance in chemistry : MRC》1977,10(1):75-78
1-Pivaloyl-2-hydroxymethylcyclopropane is studied with nuclear magnetic resonance. The C-1? C-2 configuration is determined from the 250 MHz n.m.r. spectrum (triple irradiation experiments have been performed for this purpose). Rotational isomerism around the ring-carbonyl bond is studied from the ASIS effect. Rotational isomerism around the ring-hydroxymethyl bond is studied from vicinal coupling constants over a temperature range of ?20 to +125°C. From the J(HOCH) coupling constant (in CCl4) rotamer populations of the hydroxyl group are examined and the overall conformational distribution can be established. 相似文献
19.
In order to complete the rs structure of chlorobenzene given in a preceding paper, a variety of isotopic species of this molecule were synthesized and their microwave spectra studied. This made twenty isotopic species available, enabling the determination of the geometrical parameters by a least squares method. Fitting only differences of moments of inertia either for monosubstituted species or to multiply substituted species gave the same result. They hardly differ from the ro values and agree with the rs values obtained by the Kraitchman equations. The resulting error limits were reduced, however.
The following structural parameters were obtained, C1C2 = 1.399 Å, C2C3 = 1.386 Å, C3C4 = 1.3976 Å, C1Cl = 1.7248 Å, C2H2 = 1.080 Å, C3H3 = 1.081 Å, C4H4 = 1.081 Å, C6C1C2 = 120° 16, C1C2C3 = 119°78, C2C3C4 = 120°24, C3C4C5 = 119°80, C1C2H2 = 119°45, C2C3H3 = 119°76.
The structure of the ring differs significantly from C6 symmetry. The deformation can be regarded as a compression of the position C1 while the angle of C2H2 bond is also changed. 相似文献
20.
R. Locqueneux 《International journal of quantum chemistry》1972,6(1):1-21
A general formalism is set up to apply the variation-perturbation method to the quantum theory of non-linear optical effects, in particular to the electric and magnetic birefringence (Kerr and Cotton-Mouton effects). The quantities describing these effects are obtained from the wave function Ψ of the ground state of the unperturbed molecule and the different vectors and tensors which are determined by a variation method. With this method an approximate computation of the Kerr and Cotton-Mouton constants of some simple molecules has been made. 相似文献