-Oxo anilides in Heterocyclic Synthesis: Novel Synthesis of Polyfunctionally Pyridines, Pyrimidines and Benzothiazole derivatives (original) (raw)
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Open Access Library Journal, 2015
Diazotization and coupling of acetoacetanilide derivative 1 with aromatic amines afforded the arylhydrazones 2a,b. Arylhydrazones 2a,b were treated with (DMF-DMA) to yield the pyridazine derivatives 3a,b in good yield. Pyridazinone was treated with hydrazine hydrate to yield 4a,b. Reaction of 2a with hydroxylamine hydrochloride afforded the oxime derivative 5. Similarly, the reaction of acetoacetanilide 1 with hydroxylamine hydrochloride gave 3-hydroxyimino-N-p-tolylbutyramide 8 not the pyrazolone 9. The reaction of anilide 4 with aromatic aldehydes yielded 10a,b. Also, when anilide 4 was reacted with a mixture of aromatic aldehydes, urea or thiourea afforded the pyrimidines 11a,b. The reaction of anilide 1 with active methylene reagents was also investigated. So, 1 was reacted with malononitrile to give the pyridone derivative 12. Similarly, anilide 1 was reacted with cyanoacetamide under the same reaction conditions to yield 4-methyl-2-oxo-6-p-tolylamino-1,2-dihydro-pyridine-3-carbonitrile 13 in quantitative yield. The reaction of 1 with ylidenemalononitrile depends on structure of substituent. Thus, reaction of 1 with benzylidenemalononitrile or naphthylidenemalononitrile afforded 14a,b, while that with p-anisidinemalononitrile afforded 15. Coupling 1 with diazotized 16-18 afforded 19-21 respectively. Condensing 1 and aminopyrazoles 22a,b afforded the acyclic adduct 23a,b rather than the pyrazolopyrimidine 24a,b.
Egyptian Journal of Chemistry
C OMPOUND 1 coupled smoothly with aromatic diazonium salts to yield the corresponding arylhydrazones 2a-d. Compounds 2a-d condensed with DMF-DMA in refluxing xylene to yield the pyridazinones 3a-d. Compounds 3a-d were also established based on its further reaction with some active methylene reagents and some nucleophilic reagents. So, reactions of 3a, b with malononitrile in refluxing ethanolic piperidine afforded arylidinemalononitrile 4a,b. The pyridazinone derivatives 3a, b reacted with hydrazine hydrate to afford the hydrazine derivatives 5a, b. When 3a,b were fused with hydrazine hydrate without solvent, the pyrazolo[4,3-c]-pyridazines 6a,b were obtained. Compounds 6a, b were also obtained when compounds 5a, b melt over melting point for short time. Condensation of 2a, b with ethyl cyanoacetate yield 7a, b. Similarly, reactions of 2a,b with 1 mole of malononitrile afforded the pyridazine derivatives 8a,b. While, two moles of malononitrile reacted with 2a, b in the same experimental conditions to yield the cinnoline derivative 9a, b. Reactions of pyridazine 8a,b with 1 mole of malononitrile afforded 9. Compound 2b was reacted with a mixture of arylidinemalononitrile and acrylonitrile to yield product formulated as triazole moieties 12a, b. Similarly compound 2b was reacted with a mixture of maleic anhydride and acrylonitrile in the same above experimental conditions to give 13. Also, reactions of 2b with hydroxylamine hydrochloride yield 14.
HETEROCYCLES, 2007
Cyanoacetamides (7a-c) were prepared via reacting cyanoacetic acid (5) with amines in the presence of acetic anhydride. Compounds (7a-c) coupled with benzenediazonium chloride to yield the phenylhydrazones (8a-c). These reacted with chloroacetonitrile to yield aminopyrazolecarboxamides (11a-c). Reaction of (8a,b) with hydroxylamine hydrochloride in DMF in presence of anhydrous sodium acetate afforded the amino-1,2,3-triazolecarboxamides (36a,b). Also compounds (7a-c) reacted with dimethylformamide dimethylacetal (DMFDMA) to yield the enamines (9a-c) which react with hydrazine hydrate to afford the aminopyrazoles (16a-c). Compounds (16) and (36) reacted with DMFDMA to yield the title heterocyclic derivatives.
European Journal of Chemistry, 2011
Journal of the Serbian Chemical Society, 2010
2-Chloro-4H-pyrido[1,2-a]pyrimidin-4-one (1) was utilized as a synthone precursor to prepare novel heterotricyclic systems. 2-Azido and 2-hydrazino derivatives (2 and 3) were obtained by nucleophilic replacement evolving compound 1. The hydrazine derivative 3 was transformed into the azido derivative 2 by nitrosation. Treatment of compound 3 with [bis(methylthio)methylene]malononitrile afforded 2-pyrazolylpyridopyrimidine 4. When compound 1 was reacted with 5-amino-3-(methylthio)-1H-pyrazole-4-carbonitrile, the same compound 4 was obtained with no evidence for the production of (pyrazolylamino)pyridopyrimidine 5 or pyrazolodipyridopyrimidine 6. Poly-functionalized dipyridopyrimidine 8 was obtained by reaction of compound 1 with 2-[(methylthio)-(phenylamino)methylene]propanedinitrile. Cyanoguanidine was reacted with compound 1 to afford N-pyridopyrimidinylguanidine 9, which was subjected to cyclization reaction, in presence of piperidinium acetate, to give pyridopyrimidopyrimidine 10.
Journal of Heterocyclic Chemistry, 2013
New approaches for the synthesis of some heterocyclic compounds, such as the pyridopyrimidodiazepine derivative 3, pyrazolopyrido[1,2-a]pyrimidine derivative 4, tetrazolo[1.5-a][1,8]naphthyridine derivative 9, pyrazolylpyrido[1,2-a]pyrimidine derivatives 10a,b,12, pyrrolopyrido[1,2-a]pyrimidine derivatives 14a-d, and16a,b, starting from 2-chloro-4H-4-oxo-pyrido[1,2-a]pyrimidine (1), are described.
Archives of Pharmacal Research, 1990
Abstraetl3Several new pyridine, pyridinethione, pyrazole[3,4-b]-pyridine, pyrido [l,2-a]-t,3-thiazine and pyrido[l,2-a]pyridine thione derivatives have be synthesised via the reactions of 2-methyl-3-ethoxycarbonyl-4-phenyl-5-cyano-l,4,5,6-tetrahydro-pyridine-6-one 2 with different reagents. The structures of the newly synthesised derivatives were established on the basis of elemental analyses and spectal data studies.
N-Bis(methylthio)methylenecyanamide (1) was allowed to react with ethylcyanoacetate or malononitrile in the presence of potassium carbonate in dimethylformamide to give the urea derivatives 3a, b, which on treatment with hydrazine hydrate yielded the corresponding aminopyrazole derivatives 4a, b. The cyclic amidine 5-Amino-3-ureido-1H-pyrazole-4-carboxylic acid ethyl ester (4a) is found to be useful intermediate for the synthesis of new pyrazolopyrimidine and pyrazolotriazine derivatives 5- 22a, b. The chemical structures of the synthesized compounds 3a, b- 22a, b were characterized by their elemental analyses, FT-IR, 1H 13C NMR and mass spectra.
Novel Synthesis Method of Pyrimidine and Pyrazole Derivatives
The chemistry of 2-pyrones has undergone considerable development owing to their presence in natural compounds and their application in biological and food industry. Dehydroacetic acid plays a pioneering role in the synthesis of different heterocyclic compounds such as pyrimidine, pyrazole, 1,5benzodiazepine. The choice of such compounds is mainly based on their pharmacological properties 1-3. Modified pyrimidines have keenly interested the chemist and pharmacologist because of their impact in the therapeutic field. Indeed, these compounds after some modifications showed antibiotic, anticancer, antiviral 4 and agrochemical properties 5-7. Pyrazoles, in their turn, constitute an important development in the field of fine chemistry because of their importance in medicinal chemistry or during the preparation of pesticides and insecticides 8. The pyrazole pattern is found in a large number of compounds known for their therapeutic value mainly as anti-inflammatory 9 , antitumor 10-15 hypnotic and sedative properties 16-18. Some of these structures have shown, in addition to their analgesic properties 19 and antimicrobial activity 20. In the context of the investigation dealing with the use of dehydroacetic acid 1 and its derivatives in heterocyclic synthesis, we report in this work the synthesis of new molecules (pyridopyrimidine, pyrazole) susceptible to present interesting pharmacological properties.