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Paul S. Dobbin Robert C. Hider Lalitha Venkatramani Jintana Siripitayananon Dick van der Hel 《Journal of heterocyclic chemistry》1993,30(3):723-737
A range of N-alkyl-2,6-dimethyl-4-oxopyridine-3-carboxylic acids XV have been prepared via reactions of primary alkyl amines with differing 2,6-dimethyl-4-oxopyran-3-carboxylate esters IX . The quantity of desired product formed and the character of by-products formed are determined by the natures of the amine and ester IX respectively. X-ray crystallography data for the N-ethyl analogue of XV indicates very strong intramolecular hydrogen bonding to be present, with the heterocyclic ring exhibiting considerable aromaticity. 相似文献
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L. N. Sobenina M. P. Sergeeva A. I. Mikhaleva M. V. Sigalov S. E. Korostova N. I. Golovanova V. N. Salaurov E. V. Bakhareva N. N. Vasil'eva 《Chemistry of Heterocyclic Compounds》1990,26(5):516-520
Haloform cleavage of 2-trifluoroacetyl- and N-vinyl-2-trifluoroacetylpyrroles gives pyrrole-2-carboxylic acids and their N-vinyl derivatives in good yields; most of these compounds do not melt between 120–190C, but rather decompose with CO2 evolution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 612–616, May, 1990. 相似文献
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A. V. Prosyanik S. V. Bondarenko V. I. Markov I. I. Chervin M. D. Isobaev S. D. Kushch R. G. Kostyanovskii 《Chemistry of Heterocyclic Compounds》1980,16(2):154-158
Esters of β-alkoxyamino-α-bromopropionic acids were obtained by reaction of α,β-dibromopropionic acid esters with alkoxyamines
in the presence of triethylamine at 20°C for 1 month. When the products are refluxed in acetonitrile in the presence of triethylamine,
they are converted to aziridines. Selective amidation of the alkoxyaziridines with excess dimethylamine in absolute methanol
in the presence of sodium methoxide leads to enrichment with the cis isomer. The parameters of inversion of the nitrogen atom
in the alkoxyaziridines were determined.
Communication 20 from the series “Asymetric Unbridged Nitrogen”; see [1] for communication 19.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 212–215. February, 1980. 相似文献
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A. V. Eremeev F. D. Polyak I. A. Vosekalna I. I. Chervin Sh. S. Nasibov R. G. Kostyanovskii 《Chemistry of Heterocyclic Compounds》1984,20(10):1102-1107
Individual diastereomers of a number of anilides of N-substituted aziridine-2-carboxylic acids have been obtained. Conclusions regarding the spatial structure of the compounds indicated have been drawn on the basis of the 1H NMR, 15N NMR, and CD spectra.Report 37 of the series entitled Asymmetric nonbridging nitrogen. For report 36 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1343–1348, October, 1984. 相似文献
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U Langenbeck A Mench-Hoinowski K P Dieckmann H U M?hring M Petersen 《Journal of chromatography. A》1978,145(2):185-193
As an extension of earlier work on aliphatic alpha-keto acids, a method is described for the quantitative gas chromatographic determination of urinary aromatic alpha-keto acids. The keto acids are derivatized with o-phenylenediamine to yield the quinoxalinols. These compounds are chromatographed after trimethylsilylation. The aromatic keto acids are stabilized by sodium dithionite (4 mg/ml urine) and storage below 0 degrees. The final derivatives are stable for weeks at room temperature. Low resolution mass spectra are reported. The fragmentation mechanisms are elucidated by analysis of O-trimethylsilyl-(TMS)-quinoxalinois, O-(TMS-d9)-quinoxalinois and O-TMS-6(7)-chloroquinoxalinois. 相似文献
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P. B. Terent'ev D. A. Simov V. B. Kalcheva Kh. S. Boicheva 《Chemistry of Heterocyclic Compounds》1976,12(11):1230-1233
N-Acetonylbenzoxazolones containing a substituent in the acetonyl residue, as well as their hydrazones and oximes, decompose under the influence of electron impact to give primarily fragments of N-methylene- or N-methylbenzoxazolones. For the oximes and hydrazones the characteristic ions are (M -OH) and (M — NH2), which evidently have cyclic structures. The isomeric aryl triazinones undergo fragmentation via the scheme of the retrodiene synthesis. The characteristic ions that make it possible to distinguish the isomeric benzoxazolones, arylimidazolones, and aryltriazinones were found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1493–1497, November, 1976. 相似文献
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M. Vairamani K. Ishratullah D. M. Reddy G. K. Viswanadha Rao 《Journal of mass spectrometry : JMS》1985,20(12):724-726
The electron-impact-induced mass spectra of substituted N-phenylphenoxyacetamides are discussed. The structure of the rearrangement ion at m/z 108 is investigated and compared with the molecular ion of anisole by metastable ion and corrected collisionally activated dissociation spectra. 相似文献
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The mass spectra of derivatives of uridine, adenosine, cytidine and guanosine are recorded. Derivatization techniques include permethylation, acetylation, trifluoroacetylation, trimethylsilylation and the synthesis of 2′,3′-O-isopropylidenes and 2′,3′-O-phenylboronic esters. Sequential derivatization by a selective combination of some of these procedures results in nucleosides which are blocked with a characteristic group at the cis 1,2 diol position, and, which contain other substituent groups that enhance the volatility of the compound. The specific substitution at the cis-glycol region has been shown to be particularly useful in asymmetrically derivatizing dinucleoside phosphates since certain fragment ions from their mass spectra indicate the sequence of the two nucleoside components. Sequence isomers such as adenylyl-(3′-5′)-uridine and uridylyl-(3′-5′)-adenosine can be unambiguously distinguished. 相似文献
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S. G. Pil’o V. M. Prokopenko V. S. Brovarets B. S. Drach 《Russian Journal of General Chemistry》2010,80(7):1345-1350
A convenient preparative procedure has been developed for the synthesis of previously unknown 2-aryl-5-arylsulfanyl-1,3-oxazole-4-carboxylic
acids and their functional derivatives from accessible multicenter substrates of the general formula Cl2C=C(NHCOR)C(O)OMe. The products turned out to be suitable for various subsequent transformations. Some oxazole-4-carboxylic
acid hydrazide derivatives containing a substituted oxazol-5-yl fragment at the N2 atom in the hydrazine moiety underwent recyclization on heating in acetic acid; as a result, one oxazole ring was converted
into 1,3,4-oxadiazole. 相似文献
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A. I. Ermakov Yu. N. Sheinkef V. I. Shvedov L. B. Altukhova É. S. Krichevskii A. N. Grinev 《Chemistry of Heterocyclic Compounds》1978,14(6):679-684
The behavior of compounds of the pyrazino- and piperazinoindole series under the influence of electron impact was studied. The fragmentation was examined as a function of the type of substituents attached to the nitrogen atom in the piperazine ring and the degree of saturation of the condensed rings. Deuterium labeling and model analogs were used to prove the fragmentation mechanisms. It is shown that the positive charge in the molecular and fragment ions may be localized both on the bridge nitrogen atom of the indole ring and on the N atoms of the pyrazine or piperazine ring. The characteristic fragments for each type of compound were found. The results can be used to study the structures of new derivatives of pyrazino- and piperazinoindoles or the products of their metabolism.Communication VII from the series Application of mass spectrometry in structural and stereochemical investigations. See [1] for communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 827–832, June, 1978. 相似文献
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Tatsuhiko Nakano Víctor E. Mrquez María T. Di Parsia Cecilia Surez 《Journal of mass spectrometry : JMS》1978,13(4):236-242
The mass spectra of some substituted oxadiazoles have been determined and analysed with the aid of high resolution mass spectrometry. Some characteristic and major differences between their spectra have been noted, and possible rationalizations have been advanced. The main fragmentation patterns of the 1,3,4-oxadiazole derivatives have been interpreted in terms of diazirine intermediates. Specific skeletal rearrangement processes have been observed in the spectra of the 1,3,4- and 1,2,4-oxadiazoles, and possible mechanisms are proposed. 相似文献
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The fragmentation patterns and major metastable ions of the mass spectra of the neopentyl-phosphorus derivatives [(CH3)3CCH2]3P, [(CH3)3CCH2]2P(O)H, [(CH3)3CCH2]nPX3-n (n = 1 and 2; X = H, Cl, C6H5 and CH = CH2), [(CH3)3CCH2]3PS, [(CH3)3CCH2]nP(S)R3-n (n = 1 and 2; R = C6H5 and CH = CH2), [(CH3)3 CCH2]2PCH2CH2P[CH2C(CH3)3]2, ([CH3)3CCH2]2PCH2PCH2-CH2P(H)C6H5 and [(CH3)3CCH2]2PCH2CH2P(S)(CH3)2 are described. Fragmentation of a neopentyl group by elimination of either C4H8 or CH3 is very favourable when the neopentyl group is bonded to either a tricoordinate or tetracoordinate phosphorus atom. In neopentylphosphines with two or three neopentyl groups, stepwise elimination of C4H8 from all of the neopentyl groups occurs very readily. The resulting [(CH3)nPX]+.3-n ions are often the most intense ions in the mass spectra. 相似文献
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