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1.
Fmoc-(R)-β-HomoAsp(OtBu)-OH was used for the synthesis of both (R) and (S) enantiomers of various Fmoc-protected 3-substituted 1,2,4-oxadiazole-containing β3-amino acids. The 1,2,4-oxadiazole heterocycle was formed using sodium acetate, a Fmoc-compatible and efficient catalyst for cyclodehydration. 相似文献
2.
J. G. Schantl J. Svetlik V. Kettmann 《Monatshefte für Chemie / Chemical Monthly》1994,125(12):1383-1387
Summary 4,5-Dihydro-5,5-dimethyl-3-oxo-3H-1,2,4-triazole (1) is converted to the title azoxy compound4 by peroxytrifluoroacetic acid. The structure assignment of4 is based on an X-ray analysis.Ab initio calculations were employed to rationalize the reaction path leading to the triazole-1-oxide4 and not to the expected regioisomer triazole-2-oxide3.
4,5-Dihydro-5,5-dimethyl-3-oxo-3H-1,2,4-triazol-1-oxid. Das unerwartete Regioisomere
Zusammenfassung 4,5-Dihydro-5,5-dimethyl-3-oxo-3H-1,2,4-triazol (1) wird mit Trifluorperessigsäure in die Titel-Azoxy-Verbindung4 umgewandelt. Die Strukturzuordnung von4 basiert auf einer Röntgenstrukturanalyse. Mittelsab initio-Rechnungen wird versucht zu erklären, weshalb die Reaktion zum Triazol-1-oxid4 und nicht zum erwarteten regioisomeren Triazol-2-oxid3 führt.相似文献
3.
The interaction of 4-allyl-5-phenyl-1,2,4-triazole-3-thione with iodine proceeds with the formation of a mixture of 6-iodomethyl-3-phenyl-5,6-dihydrothiazolo[2,3-c]-1,2,4-triazole and 6-iodo-3-phenyl-6,7-dihydro-5H-1,2,4-triazolo[3,4-b]-1,3-thiazine. The structures of the cyclization products obtained were established on the basis of the 1H NMR spectra of their dehydroiodinated derivatives. 6-Methyl-3-phenylthiazolo[2,3-c]-1,2,4-triazole, 3-phenyl-5H-1,2,4-triazolo[3,4-b]-1,3-thiazine, and 3-phenyl-7H-1,2,4-triazolo[3,4-b]-1,3-thiazine are formed on eliminating HI from the cyclization products. 相似文献
4.
Afifa Hafidh Fathi Touati Faouzi Hosni Ahmed Hichem Hamzaoui Sayda Somrani 《Phosphorus, sulfur, and silicon and the related elements》2018,193(3):155-163
New hybrid materials were synthesized from an inorganic precursor, (tetraethoxysilane: TEOS) and bifunctional organic precursors through the sol-gel process. Indeed, monolithic and transparent hybrid gels were obtained by the reaction of tetraethoxysilicate (TEOS) with 1,2,4-thiadiazole-3,5-diamine (1), 5-amino-1,3,4-thiadiazole-2-thiol (2), and 1H-1,2,4-triazole-3-thiol (3) in ethanol as solvent, using chloric acid (HCl 10?1M) as catalyst. It is shown that TEOS has been cross-linked with bi-functional heterocyclic compounds: (1), (2) and (3) leading to the formation of transparent and colorous gels. The characterization was realized by infrared, 29Si and 13C CP MAS NMR. The xerogels morphology and texture were studied by scanning electron microscopy (SEM) and Brunauer – Emmet – Teller method (BET). The obtained results show that organic adducts (1), (2) and (3) react with TEOS leading to gels in which Si–N and Si–S bridges were formed. According to N2-physisorption results, xerogels are mesoporous with specific surface area varied from 105 to 312 m2g?1 and their isotherms are classified as type IV. The optic and magnetic properties of hybrids were studied respectively by UV-Vis spectroscopy and RPE. This study showed that all materials are paramagnetic semiconductors. 相似文献
5.
Hıkmet Ağirbaş Yeşim Kara 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1435-1443
13C chemical shifts of C═N, C═O and C═S carbons of 3,4-disubstituted-1,2,4-oxadiazole-5-ones(thiones) and 3,4-disubstituted-1,2,4-thiadiazole-5-ones have been determined in CDCl3 solution. Exceptionally good Hammett correlations of 13C NMR chemical shifts of these carbons with σ were obtained. The negative ρ values observed (inverse substituent effects) indicate π-polarization of the C═N, C═O and C═S bonds. As expected, the long distance C═O and C═S 13C chemical shifts were found less susceptible to substituent-induced electronic changes. 相似文献
6.
Three tautomeric forms of 5-chloro-1,2,4-triazole were calculated using the Hartree-Fock (ab initio) and Meller-Plesset methods in the 6-31G(d) basis. The 35Cl NQR parameters were calculated using the occupancies of the 3p-components of the valence p-orbitals of the chlorine atom. The structure of this triazole was derived from the data obtained. 相似文献
7.
1-Phenylamino-2-imidazoline und 1,2,5,6-Tetrahydro-1,2,4-triazine aus N-(2-Chloralkyl)-imidchloriden
Jörg Beger Renate Neumann Dieter Scheller 《Monatshefte für Chemie / Chemical Monthly》1981,112(8-9):959-971
1-Phenylamino-2-imidazolines3 and 1,2,5,6-tetrahydro-1,2,4-triazines4, 5 and6 are synthesized from N-(2-chloralkyl)-imidchlorides1 and phenylhydrazines. As intermediates are obtained the hydrochlorides of amidrazones2 which cyclise. The structure of the different heterocyclic systems are determined by1H- and13C-NMR-spectroscopy. 相似文献
8.
The reaction of 6-(tert-butyl)-3-hydrazino-1,2,4-triazin-5(2H)-one with acetone and benzaldehyde yields the corresponding hydrazones. In the presence of thionyl chloride the benzaldehyde hydrazone is converted to 3-(tert-butyl)-6-phenyl-1,2,4-triazolo[4,3-b]-1,2,4-triazin-2(1H)-one and this can also be formed via the acylation of the starting hydrazinotriazinone using benzoyl chloride. 相似文献
9.
Antonio Salgado Carmen Varela Ana María García Collazo Paolo Pevarello 《Magnetic resonance in chemistry : MRC》2010,48(8):614-622
The condensation of malonoaldehyde derivatives with either a 3‐amino‐[1,2,4]‐triazole or a 3,5‐diamino‐[1,2,4]‐triazole precursor was studied. In agreement with previous reports, two different bicycles, namely, bearing the regioisomeric [1,2,4]triazolo[1,5‐a]pyrimidine ( 1 ) or[1,2,4] triazolo [4,3‐a]pyrimidine ( 2 ) structural surrogates, could be obtained. We found that, depending on the triazole precursor, only one regioisomer resulted, either of the 1 or 2 series. We also observed that these two structural surrogates could be unambiguously differentiated by indirectly measuring their 15N chemical shifts by 1H? 15N HMBC experiments. The occasional conversion of [1,2,4]triazolo[4,3‐a]pyrimidines to the [1,2,4]triazolo[1,5‐a]pyrimidine counterparts could be unequivocally determined by 15N NMR data. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
10.
M. Chakrabarty A. Batabyal M. S. Morales-Ríos P. Joseph-Nathan 《Monatshefte für Chemie / Chemical Monthly》1995,126(6-7):789-794
Summary Unambiguous1H and13C NMR assignments for 4(3H)-quinazolinones1–6 and their corresponding 4-thiones7–12 have been made. This resulted in the revision of the previous assignments for the two benzenoid carbons (C-5 and C-8) of quinazolinones1,2,4, and5. Thionation of the nucleophilic amides1–6 has been found to cause a distinct change in the13C chemical shift of particularly C-4, but also of those of C-4a, C-5, and C-8a. One-bond and several long range heteronuclear coupling constants for the compounds have also been measured.
Kernresonanzspektroskopie von 4(3H)-Chinazolinonen und 4(3H)-Chinazolinthionen
Zusammenfassung Die1H- und13C-NMR-Spektren der 4(3H)-Chinazolinone1–6 und ihrer entsprechenden 4-Thione7–12 wurden zugeordnet. Dabei zeigte sich, daß eine frühere Zuordnung der beiden benzoiden Kohlenstoffe (C-5 und C-8) der Chinazolinone1,2,4 und5 falsch war. Ersatz des Sauerstoffs durch Schwefel in den nukleophilen Amiden1–6 führt insbesondere für C-4, aber auch für C-4a, C-5 und C-8a zu einer deutlichen Änderung der chemischen Verschiebung. Heteronukleare Kopplungskonstanten über eine und über mehrere Bindungen wurden bestimmt.相似文献
11.
József Reiter László Pongó Tamás Somorai István Pallagi 《Monatshefte für Chemie / Chemical Monthly》1990,121(2-3):173-187
Summary Different functionalized alkyl 3-oxo-butyrates (2) were reacted with 5-amino-3-Q-1H-1,2,4-triazoles (1) to yield3 and4 type 1,2,4-triazolo[1,5-a]pyrimidinones. In case of2 (R
1=methyl,R
2=1-ethoxycarbonylethyl,R
3=ethyl) beside the corresponding derivative4 the unexpected 5,6-dihydro-6,8-dimethyl-7-ethoxycarbonyl-3-methylthio-1,2,4-triazolo[4,3-a]-1,3-diazepin-5(9H)-one (7) was isolated, representing a novel ring system.
Über Triazole, 19. Mitt.: Die Reaktion von 5-Amino-1,2,4-triazolen mit funktionalisierten Acetoessigestern
Zusammenfassung Verschiedene funktionalisierte 3-Oxo-buttersäurealkylester (2) wurden mit 5-Amino-3-Q-1H-1,2,4-triazolen (1) umgesetzt, wobei 1,2,4-Triazolo[1,5-a]pyrimidinone der Typen3 und4 erhalten wurden. Im Fall von2 (R 1=Methyl,R 2=1-Ethoxycarbonylethyl,R 3=Ethyl) wurde neben dem erwarteten Derivat4 das unerwartete 5,6-Dihydro-6,8-dimethyl-7-ethoxycarbonyl-3-me-thylthio-1,2,4-triazolo[4,3-a]-1,3-diazepin-5(9H)-on (7) isoliert, welches ein neues Ringsystem darstellt.相似文献
12.
通过3-取代-4-氨基-5-巯基-1,2,4-三唑(3a~3m)和2-溴-2-(1H–1,2,4-三唑-1-基)-4′-氯代苯乙酮(2)的缩合反应, 合成了13个新型3-取代-6-(4-氯苯基)-7-(1H-1,2,4-三唑-1-基)-1',2',4'-三唑[3,4-b]-1",3",4"-噻二嗪衍生物4a~4m. 化合物结构经元素分析, 1H NMR, IR和MS进行了表征. 抗菌试验表明所合成的化合物对细菌表现出中等程度的抑制活性. 相似文献
13.
O. N. Chupakhin G. L. Rusinov N. A. Itsikson D. G. Beresnev O. V. Fedorova I. G. Ovchinnikova 《Russian Chemical Bulletin》2004,53(10):2308-2313
A method of one-step C-C coupling of 1,5-bis(2,6-dimethylphenoxy)-3-oxapentane (1a) and 1,8-bis(2,6-dimethylphenoxy)-3,6-dioxaoctane (1b) with 3-methylthio- (2) and 3-amino-1,2,4-triazine (3) and 3-aryl-1,2,4-triazin-5-one (6-8) has been described. The reaction of compounds 1a,b with compounds 2 and 3 in the presence of trifluoroacetic acid results in the addition of the dimethylphenoxy group to the unsubstituted C(5) carbon atom of the triazine ring. The reactions of triazinones 6-8 with compounds 1a,b in a mixture of trifluoroacetic acid and organic anhydrides are accompanied by the acylation of the nitrogen atom adjacent to the reaction center and affords bis[(3-R-1-acyl-5-oxo-1,4,5,6-tetrahydro-1,2,4-triazin-6-yl)-2,6-dimethylphenoxy]-3-oxapentane or -3,6-dioxaoctane. The obtained adducts can smoothly be oxidized under mild conditions to form more stable products of nucleophilic hydrogen substitution in the triazine ring. The extraction and transport of Ca2+ and Mg2+ cations through an organic membrane by the compounds synthesized are discussed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2210–2215, October, 2004. 相似文献
14.
V. N. Yarovenko B. I. Ugrak M. M. Krayushkin V. Z. Shirinyan I. V. Zavarzin 《Russian Chemical Bulletin》1994,43(4):627-629
The structures of complexes formed during the transformation of amidoximes into 1,2,4-oxadiazoles by the action of nitriles in the presence of zinc chloride and HCl were studied by15N NMR spectroscopy.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 676–678, April, 1994. 相似文献
15.
A. V. Ivanov E. G. Khelkovskaya-Sergeeva T. V. Vasina O. V. Masloboishchikova L. M. Kustov P. Zeuthen 《Russian Chemical Bulletin》1999,48(7):1266-1269
The catalytic activity of superacidic systems based on SO4/ZrO2 and modified by IV Period metals in isomerization ofn-butane was studied. At low temperatures of the reaction, the introduction of Fe3+, Sc3+, Co2+, or Zn2+ ions (1%) increases the yield of isobutane by 1.5 times due to the activation ofn-butane on the sites created by the promoting ions. The addition of Cr3+, V4+, or Mn2+ (1%) decreases the catalytic activity because of a decrease in the catalyst acidity, most likely, due to the reduction of
surface sulfur species. The influence of the nature of the support and surface additives of SiO2, TiO2, and ZrO2 on the activity and selectivity of the catalytic system inn-butane isomerization was studied.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7 pp. 1276–1280, July, 1999 相似文献
16.
A. M. Hussein S. M. Sherif A. A. Atalla 《Monatshefte für Chemie / Chemical Monthly》1996,127(11):1153-1160
Summary Condensation of cyano acid hydrazide1 with cyclopentanone in refluxing ethanolic piperidine yields hydrazone2. With mixtures of aliphatic aldehydes and different active methylene reagents,2 reacts to 1,2,4-triazolo[1,5-a]pyridines (8a–f). Compound2 also reacts with arylidenes9a–g to give triazolopyridines10a–g. Reaction of2 with aromatic aldehydes affords compounds13a–c. Diazotation of2 with aryldiazonium chloride in ethanol at 0 °C leads to the azo adducts15a–d. The thieno-1,2,4-triazolopyridine16 is obtained by reaction of8a with elementary sulfur.16 undergoes cycloaddition with -nitrostyrene, maleic anhydride, N-arylmalemide, and acrylonitrile yielding the isoquinolines21–24. All new compounds have been characterized by their IR,1H NMR, and mass spectra.
Ein neuer Syntheseweg für 1,2,4-Triazolo[1,5-a]pyridine und 1,2,4-Triazolo[1,5-a]isochinoline
Zusammenfassung Kondensation des Cyanohydrazids1 mit Cyclopentanon in ethanolischem Piperidin bei Rückflußtemperatur ergibt das Hydrazon2. Mit Gemischen aus aliphatischen Aldehyden und verschiedenen Verbindungen mit aktiven Methylengruppen reagiert2 zu 1,2,4-Triazolo[1,5-a]pyridinen (8a–f). Verbindung2 reagiert außerdem mit den Arylidenen9a–g zu den Triazolopyridinen10a–g. Umsetzung von2 mit aromatischen Aldehyden führt zu den Verbindungen13a–c. Diazotierung von2 mit Aryldiazoniumchloriden in Ethanol bei 0°C ergibt die Azoaddukte15a–d. Das Thieno-1,2,4-triazolylpyridin16 erhält man durch Reaktion von8a mit elementarem Schwefel.16 geht it -Nitrostyrol, Maleinsäureanhydrid, N-Arylmaleimid und Acrylnitril eine Cycloaddition zu den Isochinolinen21–24 ein. Alle neuen Verbindungen wurden durch ihre IR-,1H-NMR- und Massenspektren charakterisiert.相似文献
17.
A. G. Sukhanova G. V. Sakovich G. T. Sukhanov 《Chemistry of Heterocyclic Compounds》2008,44(11):1368-1373
Reaction of 3-nitro-1,2,4-triazole and 5-methyl-3-nitro-1,2,4-triazole with secondary and tertiary alcohols in conc. H2SO4 takes place at the N(2) atom. Alkylation by 2-propanol occurs regioselectively to form the 1-isopropyl-3-nitro-and 1-isopropyl-3-methyl-5-nitro-1,2,4-triazoles.
As a consequence of isomerization the alkylation using cyclohexyl or tert-butyl alcohols gives respectively a mixture of regioisomers
substituted at atom N(1) (1-cyclohexyl-3-nitro-and 1-cyclohexyl-5-methyl-3-nitro-1,2,4-triazoles) and at atom N(2) (5-nitro-1-cyclohexyl-and
1-cyclohexyl-3-methyl-5-nitro-1,2,4-triazoles) and, in the second case, to 1-tert-butyl-3-nitro-1,2,4-triazole.
* For Communication 5 see [1].
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1680–1687, November, 2008. 相似文献
18.
Kozhevnikov D. N. Kataeva N. N. Rusinov V. L. Chupakhin O. N. 《Russian Chemical Bulletin》2004,53(6):1295-1300
A simple procedure was developed for the synthesis of 1,2,4-triazines and their 4-oxides containing the ClCH2, Cl2CH, or CCl3 group at position 3 by cyclization of 2-aryl-2-hydrazono-1-oximinoethanes with the corresponding chloroacetonitriles. The reaction pathway depends on the number of halogen atoms in the acetonitrile used. The reactions with trichloroacetonitrile, monochloroacetonitrile, and dichloroacetonitrile afford 3-trichloromethyl-1,2,4-triazines, 3-chloromethyl-1,2,4-triazine 4-oxides, and a mixture of the corresponding dichloromethyltriazines and their 4-oxides, respectively. The reactions of 3-trichloromethyl-1,2,4-triazines with indoles and phenols are accompanied by tele-substitution with elimination of halogen from the trichloromethyl group to give 5-indolyl- (or 5-hydroxyphenyl)-3-dichloromethyl-1,2,4-triazines. 相似文献
19.
D. L. Lipilin A. M. Churakov Yu. A. Strelenko V. A. Tartakovsky 《Russian Chemical Bulletin》2007,56(8):1566-1568
Treatment of 2-(tert-butyl-NNO-azoxy)anilines with phosgene at 20 °C was proposed as a novel route to 1,2,4-benzotriazin-3(4H )-one 1-oxides. This method involves a new reaction, viz., an intramolecular interaction of the tert-butyl-NNO-azoxy group with a C-electrophile (leading to the formation of the N(2)—C(3) bond of the triazine ring) followed by elimination
of the tert-butyl group. Complete assignment of the signals in the 1H and 13C NMR spectra of the compounds obtained was performed.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1507–1509, August, 2007. 相似文献
20.
Agata Siwek Monika Wujec Joanna Stefańska Piotr Paneth 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):3149-3159
Four 4-aryl-3-(2-methyl-furan-3-yl)-Δ2-1,2,4-triazole-5-thiones were synthesized by intramolecular cyclization of 4-aryl-1-[(2-methyl-furan-3-yl)carbonyl]thiosemicarbazides in alkaline medium. The antimicrobial activity of the synthesized triazoles was evaluated. Semiempirical calculations of geometries, energies, and QSAR parameters have been determined in the hope of gaining insight into different biological activities of closely related isomers. New RM1 parameterization has been shown to perform very well for this class of compounds. 相似文献