共查询到20条相似文献,搜索用时 15 毫秒
1.
Dückert H Khedkar V Waldmann H Kumar K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(18):5130-5137
Lewis base catalyzed [4+2] annulation reactions between electron-deficient chromone oxa- and azadienes and acetylene carboxylates provide tricyclic benzopyrones inspired by natural products. An asymmetric synthesis of the tricyclic benzopyrones was developed by using modified cinchona alkaloids as enantiodifferentiating Lewis base catalysts. 相似文献
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Afshin Yazdani-Elah-Abadi Malek-Taher Maghsoodlou Razieh Mohebat Reza Heydari 《中国化学快报》2017,28(2):446-452
A green, convenient, high yielding and one-pot procedure for the synthesis of novel spiro[benzo[a]pyrano[2,3-c]phenazine] derivatives by domino multi-component condensation reaction between 2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamines, ninhydrine, and malononitrile in the presence of a catalytic amount of 1,3-dimethyl-7H-purine-2,6-dione (theophylline) as an expedient, eco-friendly and reusable solid base catalyst under thermal, microwave irradiation and solvent-free conditions. This procedure has also been applied successfully for the synthesis of benzo[a]pyrano[2,3-c]phenazines. 相似文献
4.
Donald C. Rogness 《Tetrahedron letters》2009,50(28):4003-4139
The reaction of methyl indole-2-carboxylates and arynes affords a very efficient, high yielding synthesis of a novel indole-indolone ring system, which tolerates considerable functionality, is broad in scope, and proceeds under mild reaction conditions. 相似文献
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A rhodium-catalyzed annulation protocol towards indolo[3,2-c]-1-azaanthraenes and successive treatment with different acids, which offered diverse indolo[3,2-c]-heteroarenes, were herein demonstrated. The transition metal-mediated system offered a direct and facile approach towards the heterocyclic compounds of great significance, enjoying high efficiency and good functional groups compatibility. 相似文献
6.
Synthesis of novel electron-deficient chromone-fused dienes via phosphine catalyzed [4+2] annulation
α-Chromonyl ketoesters undergo phosphine catalyzed [4+2]-annulation reactions with acetylene carboxylates to yield tricyclic benzopyrones in good yields. Under mild acidic conditions, the tricyclic benzopyrones rearrange to provide highly substituted and electron-poor chromone-fused dienes in good yields. 相似文献
7.
A facile synthesis of 2,3-disubstituted benzofurans from ortho oxyether aroylformates has been developed. Under the mediation of DBU, the intramolecular annulation of ortho oxyether aroylformates proceeds smoothly to provide the corresponding 2,3-disubstituted benzofurans in moderate to good yields under mild conditions. Furthermore, a one-pot two-step synthesis of 2,3-disubstituted benzofurans has also been demonstrated from readily available ortho hydroxy aroylformates. 相似文献
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One-pot synthesis of pyrano[2,3-c]pyrazole derivatives via two or multicomponent condensation of β-ketoesters, hydrazine monohydrate/phenyl hydrazine, malononitrile, and substituted benzaldehydes is of great interest not only in synthetic chemistry but also in medicinal chemistry because of the tremendous biological activities, such as anticancer, anti-inflammatory, analgesic, antimicrobial, and enzyme inhibitory activities exhibited by pyranopyrazoles. This review provides extensive knowledge on novel synthetic methodologies of biologically active non-spiro/spiro-pyrano[2,3-c]pyrazole derivatives published recently. 相似文献
9.
Mallappa Beerappa 《合成通讯》2018,48(2):146-154
N-methylmorpholine N-oxide and silver oxide (Ag2O) oxidized four component reaction for the preparation of pyranopyrazole with different substituted pattern have been developed which provides rapid access to a library of compounds in good to excellent yields by using benzyl halide, malanonitrile/ethyl cyanoacetate, diethylacetylenedicarboxylate/ethyl acetoacetate and hydrazine hydrate as reactants. This transformation involves the breaking of one C?O bond and formation of 2 C–C, 2 C–N, and a C?O bond leading to the formation of a five and six membered ring in one pot operation. 相似文献
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The domino Knoevenagel hetero-Diels-Alder reaction of the O-propargylated salicylaldehydes and 4-hydroxycoumarin leads to pyrano[2,3-c]coumarins 3 and pyrano[2,3-c]chromones 4 in high yield in the presence of CuI as a Lewis acid. In all cases, the reaction was shown to exhibit high regioselectivity and form product 3 as main product. 相似文献
11.
Kudale AA Kendall J Miller DO Collins JL Bodwell GJ 《The Journal of organic chemistry》2008,73(21):8437-8447
Condensation of 3-aminocoumarin (5) with 4-nitrobenzaldehyde (8) afforded a 2-azadiene (9), which reacted with various electron-rich alkenes (10 examples) in the presence of Yb(OTf)3 to afford 1,2,3,4-tetrahydropyrido[2,3-c]coumarins. Yields were generally good, but the diastereomeric ratios were highly variable. The products arose through a formal [4 + 2] cycloaddition (inverse electron demand Diels-Alder reaction) followed by tautomerization. As such, these are examples of the Povarov reaction. A range of 1,2,3,4-tetrahydropyrido[2,3-c]coumarins was then synthesized using a three-component version of this reaction, which involves in situ formation of the 2-azadiene component. Some of these products were converted into the corresponding pyrido[2,3-c]coumarins upon treatment with various oxidants, the most effective of which proved to be nitrous gases. 相似文献
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Synthesis of pyrimido[1,2-a]benzimidazole and pyrano[2,3-c]pyrazole derivatives were achieved using polyethylene glycol (PEG-400) as promoting reaction medium in water under catalyst-free conditions at reflux and room temperature, respectively. The structure of pyrimido[1,2-a]benzimidazole was confirmed using 1H NMR, 13C NMR, DEPT, and HMBC experiments. The promising points for the present methodology are efficiency, generality, high yield, short reaction time, cleaner reaction profile, ease of product isolation, simplicity, potential of recycling reaction medium, and finally agreement with green chemistry protocols. 相似文献
13.
A new synthesis of three isomeric dihydrofuroquinolines is described. This route via ortholithiation of O-quinolyl carbamates is considerably more effective than that which proceeds via lithiation of alkoxyquinolines. 相似文献
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The base promoted four-component reaction of hydrated hydrazine, dimethyl acetylenedicarboxylate, isatines and malononitrile (ethyl cycanoacetate) in ethanol afforded polysubstituted spiro[indoline-3,4‘-pyrano[2,3-c]pyrazoles] and spiro[acenaphthyl-3,4-pyrano[2,3-c]pyrazoles] 相似文献
16.
Hassan Attia Elfahham Fathy Mohamed Abdel-Galil Yusria Rizk Ibraheim Mohamed Hilmy Elnagdi 《Journal of heterocyclic chemistry》1983,20(3):667-670
Several new pyrazolo[1,5-a]pyrimidines and pyrano[2,3-c]pyrazoles were synthesized viathe reaction of the cinnamonitrile derivatives 1a-c with 5-amino-3-phenylpyrazole ( 1 ), 3-amino-2-pyrazolin-5-one ( 2 ) and 3-amino-1-phenyl-2-pyrazolin-5-one ( 22 ). 相似文献
17.
Ronald W. Clawson Jr. 《Tetrahedron letters》2007,48(34):6019-6021
An expedient synthesis of the alkaloid koniamborine, the only to date isolated naturally occurring pyrano[3,2-b]indole is presented. The key pyrano[3,2-b]indole forming step is a palladium-catalyzed reductive N-heteroannulation of 2-(4-methoxy-2-nitrophenyl)-(4H)-pyrane-4-one. 相似文献
18.
Anna Arnoldi Giovanna Bregante Patrizia Caldirola Lucio Merlini Bruno Tamburini 《Journal of heterocyclic chemistry》1990,27(5):1169-1171
New syntheses of 4,5,6,7-tetrahydrofuro[2,3-c]pyridines and furo[2,3-c]pyrrolidine derivatives, starting from furan-3-carboxaldehyde, are reported. 相似文献
19.
《Arabian Journal of Chemistry》2019,12(5):671-679
Mn doped zirconia is utilized as an environmental-friendly and efficient catalyst for an ultrasound mediated four-component coupling reaction, containing dimethylacetylenedicarboxylate/ethyl acetoacetate, hydrazine hydrate, malononitrile, and aromatic aldehyde. These reactions were performed under green solvent conditions, to yield pyrano[2,3-c]pyrazole-3-carboxylate/pyrano[2,3-c]pyrazole-5-carbonitrile derivatives (5a–g and 7a–g) with good to excellent yields (88–98%). The structures of the compounds were identified and confirmed by 1H NMR, 15N NMR, 13C NMR, FT-IR and HR-MS spectral data. The prepared catalyst Mn/ZrO2 was synthesized and fully characterized by various techniques including P-XRD, BET, SEM and TEM analysis. The main benefits of this process are short reaction times, easy work-up, reusability of the catalyst and no chromatographic purifications. 相似文献
20.
Narsidas J. Parmar Shashikant B. TeraiyaRikin A. Patel Navin P. Talpada 《Tetrahedron letters》2011,52(22):2853-2856
A tetrabutylammonium hydrogen sulfate (TBA-HS) mediated procedure for one pot synthesis of novel benzopyran-annulated pyrano[2,3-c]pyrazoles via domino/Knoevenagel-hetero-Diels-Alder reaction has been demonstrated. 相似文献