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1.
We have established that when 5-chloro-6-[cyano(2,3-dihydro-1-R-benzo[d]azol-2-yl)methyl]-2,3-pyrazinedicarbonitriles are reacted with nucleophilic reagents (aliphatic and aromatic amines, hydrogen sulfide), annelation of the five-membered ring occurs on the [b] face of the pyrazine with formation of 6-amino-7-hetaryl-5-R-5H-pyrrolo[2,3-b]pyrazine-2,3-dicarbonitriles and 6-amino-7-(1H-benzo[d]imidazol-2-yl)thieno[2,3-b]pyrazine-2,3-dicarbonitrile respectively. Further heating with excess of acylating reagent leads to formation of a novel heterocyclic system 1H-benzo[4,5]imidazo[1,2-c]pyrazino[2',3':4,5]pyrrolo[3,2-e]pyrimidine. Reaction of vicinal dinitriles with hydrazine hydrate leads to the novel system 1H-pyrrolo[2',3':5,6]pyrazino[2,3-d]pyridazine. 相似文献
2.
Two routes describing the preparation of 4-fluoro-1H-pyrrolo[2,3-b]pyridine (4a) from 1H-pyrrolo[2,3-b]pyridine N-oxide (1) are presented. Regioselective fluorination was achieved using either the Balz-Schiemann reaction or lithium-halogen exchange. [reaction: see text] 相似文献
3.
4.
Bhawana Singh Atish Chandra Mrityunjaya Asthana Radhey M. Singh 《Tetrahedron letters》2012,53(26):3242-3244
Rapid and efficient one-pot synthesis of thiopyrano[2,3-b]quinolines is described from the reaction of 3-formyl-quinoline-2-thiones with acrylonitrile using economical organic base Et3N at room temperature. The reaction proceeded smoothly via domino Michael addition/cyclization reactions and did not require dry solvent, inert atmosphere and column chromatography purifications. 相似文献
5.
It has been found that malonodinitrile and 2-(6-R1-oxo-3,4-dihydro-2-quinazolyl)acetonitrile in the presence of triethylamine undergo hetarylation by 5,6-dichloro-2,3-pyrazinedicarbonitrile at the active methylene group to give the triethylammonium salt of 2-(3-chloro-5,6-dicyano-2-pyrazinyl)malononitrile or 5-chloro-6-cyano(6-R1-4-oxo-1,2,3,4-tetrahydro-2-quinazolylidene)methyl-2,3-pyrazinedicarbonitriles. Reaction of these with primary amines leads to annelation of the pyrrole ring at the pyrazine [b] edge to give 6-amino-5-R-5H-pyrrolo[2,3-b]pyrazine-2,3,7-tricarbonitriles and 6-amino-5-R2-7-(6-R1-4-oxo-3,4-dihydro-2-quinazolyl)-5H-pyrrolo[2,3-b]pyrazine-2,3-dicarbonitriles respectively. 相似文献
6.
Girijesh K. Verma Keshav Raghuvanshi Ram Kumar Maya Shankar Singh 《Tetrahedron letters》2012,53(4):399-402
A simple, efficient, and high yielding one-pot protocol for the synthesis of pyrimido[4,5-b]quinolines and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidines has been developed by three-component domino coupling of 6-amino-1,3-dimethyluracil, aldehydes, and cyclic 1,3-diketones in ecofriendly solvent water promoted by PTSA. The protocol avoids the use of expensive catalysts, toxic solvents, and chromatographic separation. The generality and functional tolerance of this convergent and environmentally benign method is demonstrated. 相似文献
7.
Fabien Baragona Thierry Lomberget Christian DuchampNatali Henriques Eugenio Lo Piccolo Patrizia DianaAlessandra Montalbano Roland Barret 《Tetrahedron》2011,67(45):8731-8739
Variously substituted 2,3-dihydrobenzofurans have been synthesized according to a sequential one-pot oxidation/cyclization procedure between para-aminophenol derivatives and an azadiene. 相似文献
8.
Koubachi J El Kazzouli S Berteina-Raboin S Mouaddib A Guillaumet G 《The Journal of organic chemistry》2007,72(20):7650-7655
A new and efficient method for the synthesis of 2,3,6-trisubstituted imidazo[1,2-a]pyridine derivatives using a microwave-assisted one-pot, two-step Suzuki/heteroarylation or one-pot, three-step cyclization/Suzuki/heteroarylation was developed. Polysubstituted compounds are obtained in good yield from 2-amino-5-halogenopyridines, 2-halogenocarbonyl derivatives, boronic acids, and heteroaryl bromides. 相似文献
9.
A concise and efficient method for the preparation of 6,7-disubstituted-5H-pyrrolo[2,3-b]pyrazines via a palladium-catalyzed heteroannulation is reported. Both conventional and microwave heating were used to perform the reactions, with the latter showing dramatically improved results. 相似文献
10.
Roya Shahnaei Hassan Kabirifard Parinaz Fathololoomi 《Journal of heterocyclic chemistry》2020,57(2):550-555
An efficient one-pot three-component reaction of 4-benzoyl-5-phenylamino-2,3-dihydrothiophene-2,3-dione, diaminomaleonitrile, and alcohols with hetero-atom substituents or several hydroxyl groups in acetonitrile solvent under reflux led to the formation of 5-(2-substituted ethoxy or propoxy-2-phenyl-1-N-phenylthiocarbamoylethenyl)-6-oxo-1,6-dihydropyrazine-2,3-dicarbonitrile derivatives in good yields. 相似文献
11.
Research on Chemical Intermediates - In this study, a facile and rapid method was developed to synthesize intensely organoselenium compounds, namely ethylseleno[2,3-b]pyridine carboxylate,... 相似文献
12.
Cho SD Park YD Kim JJ Lee SG Ma C Song SY Joo WH Falck JR Shiro M Shin DS Yoon YJ 《The Journal of organic chemistry》2003,68(20):7918-7920
Pyrido[2,3-b][1,4]oxazin-2-ones are conveniently prepared in excellent yields by a one-pot annulation of N-substituted-2-chloroacetamides with 2-halo-3-hydroxypyridines with use of cesium carbonate in refluxing acetonitrile. The key transformation features a Smiles rearrangement of the initial O-alkylation product and subsequent cyclization. 相似文献
13.
Palladium-catalyzed reaction of propargylic carbonates with carbon nucleophiles offers an efficient, direct route to highly substituted indenes. The reaction conditions and the scope of the process are examined, and a possible mechanism is proposed. [reaction: see text] 相似文献
14.
Mohammad Mehdi Ghanbari 《Green Chemistry Letters and Reviews》2016,9(4):203-207
A simple and eco-friendly method for the synthesis of novel imidazo[2,1-b][1,3]thiazin derivatives has been developed via the one-pot, three-component and solvent-free reaction of thiohydantoins, aromatic aldehyde and 5,5-dimethylcyclohexane-1,3-dione in the presence of catalytic amount of p-toluene sulfonic acid, in good and excellent yields. 相似文献
15.
The one-pot synthesis of various functionalized thieno[2,3- b]thiopyran-4-ones from readily available beta-keto epsilon-xanthyl phosphonates has been accomplished by combining a Horner-Wadsworth-Emmons olefination with a base-induced intramolecular domino cyclization/thio-Michael addition. The use of cyclic ketones in this transformation allowed a facile access to novel spiro-type thieno[2,3- b]thiopyran structures. 相似文献
16.
A one-pot, three-component condensation reaction of an isatin, isoxazole, and barbituric acid in water to give spirooxindoles in high yields, at 70 °C temperature, using a catalytic amount of p-toluene sulfonic acid, is described. 相似文献
17.
A practical and general one-pot synthesis of 1-substituted-10-methyl-1,2,3,4-tetrahydropyrazino[1,2-a]indoles is described. The approach uses 2-(3-methyl-1H-indol-1-yl) ethylamine, benzotriazole and aldehydes in the presence of catalytic amount of acid catalysts (AlCl3, ZnCl2, ZnBr2, p-TsOH, CH3SO3H) and proceeds in high yields via iminium cation intramolecular cyclization. The mechanism of the observed intramolecular cyclization reaction has been investigated theoretically by means of PM3 semiempirical method and results were consistent with the experimental results. 相似文献
18.
2,3-Disubstituted benzo[b]thiophenes have been prepared in excellent yields via coupling of terminal acetylenes with commercially available o-iodothioanisole in the presence of a palladium catalyst and subsequent electrophilic cyclization of the resulting o-(1-alkynyl)thioanisole derivatives. I(2), Br(2), NBS, p-O(2)NC(6)H(4)SCl, and PhSeCl have been utilized as electrophiles. Aryl-, vinyl-, and alkyl-substituted terminal acetylenes undergo this coupling and cyclization to produce excellent yields of benzo[b]thiophenes. (Trimethylsilyl)acetylene also undergoes this coupling/cyclization process with I(2), NBS, and the sulfur and selenium electrophiles to afford the corresponding 2-(trimethylsilyl)benzo[b]thiophenes. However, cyclization of the silyl-containing thioanisole using Br(2) affords 2,3-dibromobenzo[b]thiophene. 相似文献
19.
A novel approach to one-pot synthesis of dihydrofuro[3′,4′:5,6]pyrido[2,3-c]pyrazole and indeno[2′,1′:5,6]pyrido[2,3-c]pyrazole derivatives have been investigated using organocatalysts that are recyclable. This new protocol has the advantages of environmental friendliness, higher yield, low cost, as well as convenient operation. The catalytic efficiency of various small organocatalysts such as l-proline, trans-4-hydroxy-l-proline, l-thiaproline, cinchonidine, (+)-cinchonine, and dl-2-phenylglycine has also been studied. 相似文献