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1.
Comparative study on the proton and carbon NMR spectra for a series of - and -acyl substituted monohydroxypyridines (C5H4NO: =-H, -CHO, -COCH3, -COC(CH3)3, -COCF3, -COC6H5, -SO2CH3, -SO2C6H4CH3 is reported. p]Characteristic 1H, 13 NMR and IR spectral features allow simple and unambiguous distinction between the isomeric - and/or -acyl-derivatives of 2-, 3- and 4-hydroxypyridines, so that both forms can clearly be identified when tautomeric equilibria occur, since the tautomerism rate is slow on the NMR time scale 相似文献
2.
BF3-mediated formation of a 2,5-oxygen bridge from carotenoids with 2-hydroxy-β-type end groups accompanied by dehydrogenation and shift of the polyene system is reported. The configuration of the Δ6,6′ double bonds are established by 1H NMR. 相似文献
3.
The preparation of a variety of benzo[c]cinnolines as well as benzo[c]cinnoline monoxides and dioxides by reduction of the corresponding 2,2-dinitrobiphenyls with hydrogen and Raney nickel of low activity is described. The detailed procedures developed produce superior yields of benzo[c]cinnoline monoxides and dioxides. The structure of some intensely-colored red-violet amino, alkylamino, and hydroxybenzo[c]cinnoline monoxides and dioxides is discussed and these are compared with the essentially colorless alkoxyl and acetylamino derivatives. The long wave length band in the U. V. spectrum of the colored compounds is compared. 相似文献
4.
The reactions of N-sulfinylsulfonamides with dimethyIketen-N-phenylimine furnish 3- sulfonylimino-1,2-thiazetidin-1-oxides (e.g. ) instead of the previously reported 3-isopropylidene-1,2,4-thiadiazetidin-1-oxides (e.g. ). 相似文献
5.
L.J. Goad F.-X. Garneau J.-L. Simard J.W. ApSimon M. Girard 《Tetrahedron letters》1985,26(29):3513-3516
- 14α-Methyl-5α-cholest-9(11)-en-3β-ol () and 4α,14α-dimethyl-5α-cholest-9(11)-en-3β-ol () have been isolated from the sea cucumber and characterised by 1H NMR, 13C NMR and mass spectrometry. Lanost-9(11)-en-3β-ol () has also been tentatively identified. The relevance of this series of Δ9(11)-sterols to holothurin biosynthesis is briefly discussed. 相似文献
6.
G.W. Buchanan K. Bourque J.W. Bovenkamp A. Rodrigue R.A.B. Bannard 《Tetrahedron letters》1984,25(36):3963-3966
From 13C NMR coalescence temperature measurements, free energies of activation for degenerate ring reversal in two configurationally isomeric dicyclohexano-18-crown-6 ethers have been determined to be . 10.2 kcal/mole, with higher barriers for the 1:1 complexes with potassium phenoxide. 相似文献
7.
5-Nitropyrimidine undergoes inverse Diels-Alder cycloadditions with ketene_N,N-, -O,O- acetals and enamines resulting in pyridine derivatives. The 1H NMR evidence for the -N,N-diethyl-aminopropyne cycloadduct formation is presented. 相似文献
8.
The addition of phenylhydrazine to phenylazo-alkenes yields α-(1-phenylhydrazino)-phenylhydrazones . The reaction of phenylhydrazine with α-halogenated carbonyl compounds affords either or the isomeric α-(2-phenylhydrazino)-phenylhydrazones . Structures and (>N-NH2 and-NH-NH- groups, respectively) can be differentiated by 1H NMR in DMSO-D6 solution. Possible pathways of the reactions leading to either or are discussed. Compounds are found to be precursors of phenylosazones . 相似文献
9.
Bianca F. Bonini Elisabetta Foresti Rino Leardini Gaetano Maccagnani Germana Mazzanti 《Tetrahedron letters》1984,25(4):445-448
Silylated thiirans upon oxidation with peroxyacids do not give exclusively the corresponding S-oxides but, in addition some products derived from ring opening. The stereochemistry of the oxidation to thiiran-1-oxides is to the silyl group as demonstrated by X-ray analysis. 相似文献
10.
The proton NMR of a new hydrate as a powder was studied between ?140 and 100°C. The lattice can be considered as “rigid” at temperatures below ?80°C. The structural water corresponding to the above formula is coordinated in the form of water molecules. Above ?80°C it undergoes thermally activated hindered rotation. The compound also retains adsorbed surface “water,” partly in the form of strongly bonded OH groups, partly in the form of water molecules. Degassing at 175°C and 10?4 Torr removes the adsorbed molecular water but leaves OH groups bonded to the surface. 相似文献
11.
I. A. Grigor'ev I. A. Kirilyuk L. B. Volodarskii 《Chemistry of Heterocyclic Compounds》1988,24(12):1355-1362
4H-Imidazole 1,3-dioxides and 4H-imidazole 3-oxides were obtained by oxidation of 1-hydroxy-3-imidazoline 3-oxides and 1-hydroxy-3-imidazolines with lead and manganese dioxides or the stable nitroxyl radical, while 4H-imidazole 1-oxides were obtained by thermal decomposition of 1-acetoxy-3-imidazoline 3-oxides. Facile oxidation of the ethyl group in 5-ethyl-4H-imidazole 1,3-dioxide and the formation of 5-acetyl-4H-imidazole 1,3-dioxide and 5-acetyl-4H-imidazole 3-oxide were observed. It is shown that a strictly determined region of chemical shifts of the C(2), C(5), and C(4) atoms is characteristic for each group of 4H-imidazole N-oxides in the 13C NMR spectra; this makes it possible to clearly establish the position of the N-oxide oxygen atom.See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1640–1648, December, 1988. 相似文献
12.
Five different 2-pyrrole-1-oxides have been prepared by dehydrogenation of their corresponding pyrroline-1-oxide presursors and characterized by 1,3-dipolar cycloadditions with dimethyl ethyne dicarboxylate and/or N-phenyl maleic imide. 相似文献
13.
Youichiro Naito Yoshihisa Inoue Taizo Ono Yoshio Arakawa Chikara Fukaya Kazumasa Yokoyama Yoshiro Kobayashi Kouichi Yamanouchi 《Journal of fluorine chemistry》1984,26(4):485-497
Electrochemical fluorination of N-methyldecahydroquinoline afforded mainly a mixture of and N-(F-methyl)-F-decahydroquinoline, their rearranged isomers and F-propyl-F-cyclohexane arising from the cleavage at carbon-nitrogen bonds, in a ratio of approximately 2:4:6:3. N-Methyldecahydroisoquinoline was also fluorinated electrochemically to give a mixture of and N-(F-methyl)-F-decahydroisoquinoline, their rearranged isomers and 1-(F-ethyl)-2-(F-methyl)-F-cyclohexane in a ratio of approximately 4:4:6:1. No correlation was found between the and ratio of starting materials and that of the corresponding perfluorinated amines. Fluorination of N-methyl-1,2,3,4-tetrahydroquinoline gave much lower yields. 相似文献
14.
Bryce V. Johnson Daniel P. Sturtzel Joyce E. Shade 《Journal of organometallic chemistry》1978,154(1):89-111
Primary amines react with a variety of cationic and neutral iron isocyanide complexes to yield structural and rotational diaminocarbene isomers characterized by variable temperature 1H and 13C NMR spectra. Structural isomers result from the conversion of amines to isocyanide ligands via the base-catalyzed nucleophilic attack of initially formed diaminocarbenes on isocyanides substituents, the effect on isomer populations is often marked. Factors influencing structural and rotational isomeric preferences are discussed. 相似文献
15.
A. San Feliciano A.F. Barrero M. Medarde J.M. Miguel del Corral A. Aramburu Aizpiri F. Sánchez-Ferrando 《Tetrahedron》1984,40(5):873-878
Following a preliminary comunication on Asteriscunolide A (the first reported natural humulanolide), three more configurationally and/or conformationally isomeric Asteriscunolides ( B, C and D ) from the same plant ( L.) are described. The absolute configurations and the stable conformations of all four Asteriscunolides are established by an array of spectroscopic methods (CD, 1H and 13C NMR) without resorting to X ray analysis. 相似文献
16.
The N-hydroxyazetidines and are prepared startinfrom 2,3-dihydroazete 1-oxides ( and 0 by reduction with sodium borohydride and by reaction with a nucleophile, respectively. The N-thydroxyazetidines and can be oxidized with mercury (II) oxide to the corresponding nitrones ; oxidation of the N-hydroxyazetidine (unsubstituted at C-4) with equivalent of lead tetraacetate tyields the N-tacetoxy β-lactam . 相似文献
17.
Aqueous sodium peroxide oxidises the conjugated Δ4-3-ketosteroids - to the corresponding Δ4-3-4-diones in good yield. Saturated carbonyl and alcohol groups are not affected by the reaction. 相似文献
18.
Enamino-thiones 1 prepared from the corresponding enaminones by thiation with Lawesson's Reagent, were allowed to react with 2-chloroacrylonitrile and dimethyl acetylenedicarboxylate giving dihydro-2-thiopyrans, 2, and 4-thipyrans, 3, respectively. The reaction of 1a with ethyl propiolate at room temperature afforded 4-thipyrans, 4a, which on standing rearranged to 2-thiopyran, 5a(1, 3 amide shift). The reaction of 1b with ethyl propiolate produced 4b and 5b. Some of the 13C NMR data are reported. 相似文献
19.
Fluorosilanes react with -lithio-2,4,6-trimethyl-aniline with LiF elimination and substitution. Lithium salts are obtained by the reaction of N-(fluoro-diorganylsilyl)-2,4,6-trimethylanilines with butyllithium. Further reactions of these lithium salts with fluorosilanes gives bis(fluorosilyl)-anilines. The 19F NMR spectra of the N-(fluorosilyl)-N-(di-fluorosilyl)anilines with chiral silicon and bulky substituents show AB systems for the SiF2 groups. Analyses for C and H, NMR and mass spectra are reported for all compounds. 相似文献
20.
Sadao Miki Toshinobu Ohno Hideaki Iwasaki Zen-ichi Yoshida 《Tetrahedron letters》1985,26(29):3487-3490
Co(II)TPP1 - catalysed isomerization of a series of electronegative substituted quadricyclanes() to the corresponding norbornadiene() was found to proceed via radicophilic attack of the metal to . 相似文献