Synthesis of pyridazino(4,5-e)(1,3,4)thiadiazines and the ring contraction to pyrazolo(3,4-d)pyridazines through extrusion of sulfur.

Kaji, Koichi; Nagashima, Hiromu; Nagao, Sigeto; Tabashi, Keizo; Oda, Hirohisa

doi:10.1248/cpb.32.4437

Cited by 23 publications

(5 citation statements)

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“…Pyridazines comprise a very interesting class of heteroaromatics because of their significant biological activities [9][10][11][12]. So, enaminones 2a,b coupled with 4-nitrophenyldiazonium salt in the presence of sodium hydroxide to yield 3-(benzofuran-5-yl)-2-[(4-nitrophenyl)-hydrazono]-3-oxo-propanals 8a,b which are excellent precursors for the synthesis of pyridazine derivatives.…”

Section: Resultsmentioning

confidence: 99%

“…In particular, derivatives of this system represent a new class of HIV protease inhibitors [7,8]. Significant biological activities are also associated with substituted pyridazines [9][10][11][12], pyridones [13], pyrazoles [14,15], and isoxazoles [16,17]. In view of these facts and in continuation of our work on the synthesis of heterocyclic compounds derived from the naturally occurring furochromones (visnagin and khellin) of pharmacological interest [18,19], it was worthwhile to synthesize new benzofuran derivatives by incorporating these biogenic moieties.…”

Section: Introductionmentioning

confidence: 99%

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Benzofuranyl‐pyran‐2‐ones, ‐pyridazines, and ‐pyridones from naturally occurring furochromones (visnagin and khellin)

Keshk

2004

Heteroatom Chemistry

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Benzofuranyl‐pyran‐2‐ones, ‐pyridazines, and ‐pyridones from naturally occurring furochromones (visnagin and khellin)

Keshk

2004

Heteroatom Chemistry

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“…Namely, the halogenation was conveniently accomplished for the 1,4-dihydro-1methylpyridazino [3,4-b]quinoxaline-4,4-dicarboxylates 8a [5] and 8b using N-bromosuccinimide, bromine, or N-chlorosuccinimide, since compounds 8a,b include a hydrazone moiety [9,10] in the N 1 -N 2 -C 3 of the pyridazine ring (Chart 1).…”

Section: Methods For the Synthesis Of Compounds 6a-dmentioning

confidence: 99%

Quinolone analogues 6 [1‐5]. Synthesis of 3‐halogeno‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones

Kurasawa

Satoh

Matsuzaki

et al. 2003

Journal of Heterocyclic Chem

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The reaction of the quinoxaline N-oxides 7a,b with diethyl ethoxymethylenemalonate gave the 1-methylpyridazino [3,4-b]quinoxaline-4,4-dicarboxylates 8a,b, whose reaction with N-bromosuccinimide or N-chlorosuccinimide afforded the 3-halogeno-1-methylpyridazino [3,4-b]quinoxaline-4,4-dicarboxylates 9a-d. The reaction of compounds 9a-d with hydrazine hydrate resulted in hydrolysis and decarboxylation to provide the 3-halogeno-1-methylpyridazino[3,4-b]quinoxaline-4-carboxylates 10a-d, whose reaction with nitrous acid effected oxidation to furnish the 3-halogeno-4-hydroxy-1-methylpyridazino[3,4-b]quinoxaline-4-carboxylates 11a-d, respectively. The reaction of compounds 11a-d with hydrazine hydrate afforded the 3-halogeno-1-methylpyridazino[3,4-b]quinoxalin-4-ols 12a-d, whose oxidation provided the 3-halogeno-1methylpyridazino[3,4-b]quinoxalin-4(1H)-ones 6a-d, respectively. Compounds 6a-d had antifungal activities in vitro. J. Heterocyclic Chem., 40, 837 (2003). Introduction.In previous papers [1-5], we have reported the synthesis of the 1-alkylpyridazino[3,4-b]quinoxalin-4-ones 1-5 (Scheme 1) as candidates of antimicrobial quinolone analogues. Since the 3-carboxylic acid derivatives 1 [1] showed only weak antibacterial activities, we produced the methylene-inserted carboxylate and carboxylic acid derivatives 2a,b [2] and then the 3-alkyl derivatives 3 [3] and 4 [4]. In these modifications, we found that compounds 1 and 2 had similar antibacterial activities, but compounds 3 and 4 exhibited better antibacterial activity [5] than those of compounds 1 and 2.

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“…Polyfunctionally substituted heteroaromatics are interesting as potential agrochemicals [1][2][3], pharmaceuticals [4,5] and intermediates for the preparation of dyes [6,7]. Specially condensed pyridazinones are biologically interesting molecules and their chemistry is now receiving considerable interest [8][9][10][11][12][13][14][15]. In conjunction with our interest in the synthesis of azines and condensed azines [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

-Oxo anilides in Heterocyclic Synthesis: Novel Synthesis of Pyridazinones, Pyrazolopyridazines, and Cinnolines

et al. 2018

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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.

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Synthesis of pyridazino(4,5-e)(1,3,4)thiadiazines and the ring contraction to pyrazolo(3,4-d)pyridazines through extrusion of sulfur.

Cited by 23 publications

References 0 publications

Benzofuranyl‐pyran‐2‐ones, ‐pyridazines, and ‐pyridones from naturally occurring furochromones (visnagin and khellin)

Benzofuranyl‐pyran‐2‐ones, ‐pyridazines, and ‐pyridones from naturally occurring furochromones (visnagin and khellin)

Quinolone analogues 6 [1‐5]. Synthesis of 3‐halogeno‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones

-Oxo anilides in Heterocyclic Synthesis: Novel Synthesis of Pyridazinones, Pyrazolopyridazines, and Cinnolines

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