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1.
A facile copper(I)-catalyzed tandem reaction for the synthesis of 4,5-dihydropyrazolo[1,5-a]quinolines and pyrazolo[1,5-a]indoles is reported here. High efficiency and good yields are displayed in this transformation under mild reaction conditions. 相似文献
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V. V. Kuz'menko V. N. Komissarov A. M. Simonov 《Chemistry of Heterocyclic Compounds》1980,16(6):634-637
2,4-Disubstituted pyrazole[1,5-a]benzimidazoles were obtained by the action of carboxylic acid anhydrides on 1-amino-2-methyl-3-alkylbenzimidazolium
salts in the presence of potassium carbonate.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 814–817, June, 1980. 相似文献
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An efficient asymmetric synthesis in nine steps of natural (−)‐pumiliotoxin C ( 1 ), a decahydroquinoline alkaloid found in the skin of Central American frog species, is presented. The enantiomerically pure starting material (S)‐norvalinol ( 3 ), obtained from commercial (S)‐norvaline, was cyclized in a one‐pot procedure to the tosylated aziridine 5 . Ring opening with propargylmagnesium bromide led to the acetylenic sulfonamide tosylamide 6 , free of the allenic isomer. Compound 6 was methylated on the acetylenic C‐atom, reduced, and deprotected with Na in liquid NH3 to give the (E)‐configured unsaturated amine 8 , which was condensed with crotonaldehyde to the imine 9 and N‐acylated with isobutanoyl chloride to the key intermediate 2 . Intramolecular Diels‐Alder reaction furnished a diastereoisomeric mixture of N‐protected octahydroquinolines 10 . After catalytic hydrogenation and cleavage of the amide, natural 1 was obtained as the main product in 25% overall yield; 3.2% of its isomer 11 with the inverse configurations in position 4a, 5, and 8a was also isolated. 相似文献
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Igor Philippov Yuriy Gatilov Alina Sonina Aleksey Vorobev 《Molecules (Basel, Switzerland)》2022,27(22)
A series of pyrazolo[1,5-a]pyridine-3-ylphosphonates were prepared with moderate to good yields by the oxidative [3+2]cycloaddition of 2-subtituted ethynylphosphonates with in situ generated pyridinium-N-imines and their annulated analogs. 2-Aliphatic and 2-Ph acetylenes demonstrate low activity, and the corresponding pyrazolopyridines were achieved with a moderate yield in the presence of 10 mol% Fe(NO3)3·9H2O. At the same time, tetraethyl ethynylbisphosphonate, diethyl 2-TMS- and 2-OPh-ethynylphosphonates possess much greater reactivity and the corresponding pyrazolo[1,5-a]pyridines, and their annulated derivatives were obtained with good to excellent yields without any catalyst. 2-Halogenated ethynylphosphonates also readily reacted with pyridinium-N-imines, forming complex mixtures containing poor amounts of 2-halogenated pyrazolopyridines. 相似文献
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《Tetrahedron》1988,44(23):7155-7162
5-Substituted 3-amino-1H-pyrazole-4-carbonitriles 2a-d react with appropriate biselectrophilic reagents in the presence of (TEA) to give the substitution products pyrazolo[1,5-a]pyrimidines 4a-d, 6a-d and pyrazolo[1,5-a ]1,3,5-triazines 8a-d. Compounds 6a and 8a react with secondary amines to 10a-c and 11a-c. Treatment of 2a with malonodinitrile results in the substituted pyrazolo-[1,5-a]pyrimidine 16. Condensation of 2a, 2c and 2d with ethyli-dene-malodintriles leads to racemic dihydro-pyrazolo[1,5-a] pyr-imidines 18a-e. Reaction of diene 20 with the heterodienophile 21 leads to formation of Diels-Alder adduct 22. 相似文献
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Organocatalytic Atroposelective Intramolecular [4+2] Cycloaddition: Synthesis of Axially Chiral Heterobiaryls
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Yidong Liu Xiaoyan Wu Shan Li Lu Xue Chunhui Shan Zhengxing Zhao Prof. Dr. Hailong Yan 《Angewandte Chemie (International ed. in English)》2018,57(22):6491-6495
The enantioselective construction of axially chiral aryl‐naphthopyran skeletons was realized by organocatalytic atroposelective intramolecular [4+2] cycloaddition of in situ generated vinylidene ortho‐quinone methides, from 2‐ethynylphenol derivatives, with alkynes. Through this method, the heteroatropisomers were obtained with excellent yields and enantioselectivities. Moreover, a speculative model of the stereochemical outcome is proposed based on preliminary mechanistic studies. The products having various functional groups can be easily transformed into valuable intermediates as either potential ligands or organocatalysts. 相似文献
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A convenient and sustainable synthesis of pyrazolo[1,5-a]quinazolin-5(4H)-ones and [1,2,4]triazolo[1,5-a]quinazolin-5(4H)-one through copper-catalyzed cascade reactions of 2-bromobenzoates with 1H-pyrazol-5-amines or 1H-1,2,4-triazol-5-amine under ligand-free conditions in water is presented. It is notable that aqueous medium turned out to be crucial for the chemoselective formation of the title compounds. Compared with literature protocols, this new method showed advantages such as simple and sustainable procedure, commercially available starting materials, and convenient reuse of the reaction medium together with the copper catalyst. 相似文献
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Mohamed Hilmy Elnagdi Ezzat M. Zayed M. A. Elsayed Khalifa Said A. Ghozlan 《Monatshefte für Chemie / Chemical Monthly》1981,112(2):245-252
Diazotised 5-amino-3-methyl-4-phenyloyrazole (1) reacted with active methylene reagents and with -naphthol to yield the pyrazolo[1,5-c)-1,2,4-triazine derivatives2a-e and5. Compound1 reacted with benzoyl isothiocyanate and with phenyl isothiocyanate to yield the corresponding pyrazol-5-ylthiourea derivatives6a, b. 5a was converted into the thiourea derivative8 by the action of acids or alkalies. A synthesis of 2-methyl-3-phenyl-4,5,6,7-tetrahydropyrazolo[1,5-a]-pyrimidin-5-one from the reaction of -phenylacetoactonitrile (3-oxo-2-phenyl-butyric nitrile) and -cyanoethylhydrazine is reported.
Reaktionen mit heterocyclischen Amidinen, VII: Synthese einiger neuer Pyrazolo[1,5-c]-1,2,4-triazine, Pyrazolo[1,5-a]-1,3,5-triazine und Pyrazolo[1,5-a]pyrimidine
Zusammenfassung Diazotiertes 5-Amino-3-methyl-4-phenylpyrazol (1) reagiert mit einer aktiven Methylenkomponente und -Naphthol zu den Pyrazolo[1,5-c]-1,2,4-triazin-Derivaten2a-e und5. 1 ergibt mit Benzoylisothiocyanat und Phenylisothiocyanat die entsprechenden Pyrazol-5-yl-thioharnstoffe6a, b. 5a wurde mittels Säure oder Base in das Thioharnstoffderivat8 umgewandelt. Es wird über eine Synthese von 2-Methyl-3-phenyl-4,5,6,7-tetrahydropyrazolo[1,5-a]-pyrimidin-5-on aus -Phenylacetoacetonitril (3-Oxo-2-phenyl-butyronitril) und -Cyanoethylhydrazin berichtet.相似文献
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The 1,2,4-triazolo[1,5-a]pyrimidine-2-sulfonamides are a new class of highly active herbicides. A novel cyclization method for the synthesis of these compounds is discussed. 相似文献
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Synthesis of 6-chlorotetrazolo[1,5-a]quinazoline and 6-chloro-4,5-dihydrotetrazolo[1,5-a]quinazoline
Skryl’nikova M. A. Khramchikhin A. V. Krivchun M. N. 《Russian Journal of General Chemistry》2017,87(4):885-886
Russian Journal of General Chemistry - Reaction of 5-aminotetrazole triethylammonium salt and 2-fluoro-6-chlorobenzaldehyde resulted in the formation of 6-chlorotetrazolo[1,5-a]quinazoline instead... 相似文献
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Alí Hadi Nazario Martín Carlos Seoane Jos L. Soto Armando Albert Flix Cano 《Journal of heterocyclic chemistry》1992,29(5):1229-1235
A one step synthesis of novel piperidinium 2-aryl[1,2,4]triazolo[1,5-a]pyridinides 6 from 2′-benzoyl-2-cyanoacetohydrazide (2) and α-substituted cinnamonitriles 3 is described. The reaction takes place by 6-exodig cyclization followed by an 5-exo-trig process to afford salts 6 . The X-ray diffraction of compound 6a reveal that the cation is strongly linked to the anion by hydrogen bonds and a characteristic partial stacking motive. 2-Aryl[1,2,4]triazolo[1,5-a]pyridines were obtained from salts 6 by treatment with hydrochloric acid. 相似文献
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1-Carbethoxythiocarbamoyl-5-amino-1,2,4-triazoles and N-(1,2,4-triazol-5-yl)-N-carbethoxythioureas are formed in the reaction of 5-amino-1,2,4-triazoles with carbethoxyisothiocyanate. The triazole derivatives obtained are cyclized to substituted sym-triazolo-[1,5-a]-sym-triazines in alkaline media.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 276–280, February, 1973.See also [1,2]. 相似文献
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A novel 2-methylsulfanyl-4H-[1,2,4]triazolo[1,5-a]quinazolin-5-one was synthesized using dimethyl-n-cyanoimidodithiocarbonate and 2-hydrazinobenzoic acid as building blocks. Chemical transformation of the inherent lactam moiety in the targeted 2-methylsulfanyl-[1,2,4]triazolo[1,5-a]quinazolin-5-one offered access to a variety of derivatives. 相似文献