La Synthèse De Quelques Nouvelles Pyridazines Bicycliques

Erichomovitch, Lucien; Chubb, Francis L.

doi:10.1139/v66-313

Cited by 19 publications

(5 citation statements)

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“…Recrystallization from petroleum ether yielded white needle crystals (4.4 g, mp 82-83°). This compound is referred to as 8a:'mass spectrum m/e (rel intensity) 262 (70), 236 (20), 231 (18), 203 (67), 172 (19), 171 (100), 144 (18), 116 (17), 103 (26), 78 (59), 77 (26), 59 (80); ir 2200 (C=N), 1725 and 1750 (C=0), 810, 960, 1460, and 1620 cm"1 (isoxazole ring23); uv 205 nm (log « 3.93) (isoxazole ring15), 272 (4.29) (diene).…”

Section: Methodsmentioning

confidence: 99%

Photoreaction of benzofurazan and dimethyl Acetylenedicarboxylate. Synthesis of isomeric isoxazoles. Carbon-13 nuclear magnetic resonance spectra of isoxazoles and oxazoles

Yavari¹,

Esfandiari²,

Mostashari³

et al. 1975

J. Org. Chem.

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3. o-Cyanophenol from the Sodium Salt of syn-o-Nitrobenzaldoxime. A reaction mixture similar to IC employing the sodium salt of syn-o-nitrobenzaldoxime8 (1.13 g, 6 mmol), o-nitrobenzonitrile (20 mg, 0.14 mmol), freshly ground potassium hydroxide (338 mg, 6 mmol), and MezSO (20 ml) stirred at room temperature for 8 hr and worked up as in IC gave 500 mg (66%) of o-cyanophenol, mp 94-95O (lit.Io mp 98O). Piperonylonitrile. A. From Isolated Piperonaldoxime.The oxime employed, prepared quantitatively in aqueous ethanol, melted at 107-110' (lit." syn isomer 112O, anti isomer 146O); NMR [(CD&SO] 6 8.07 (s, 1, HC=N), 11.01 (s, 1, NOH). A mixture of the oxime (1 g, 6 mmol), p-nitrobenzonitrile (900 mg, 6.1 mmol), freshly ground potassium hydroxide (676 mg, 12 mmol), and 20 ml of MezSO was stirred at room temperature for 3-4 hr. The mixture was poured into ice water (150 ml) and the solution was acidified and extracted with ether. The ethereal extract was successively washed with cold 5% aqueous sodium hydroxide and water. After drying (MgS04) and removal of the solvent in vacuo, 807 mg (92%) of the nitrile was obtained. Recrystallization from ethanol-water gave analytically pure material (645 mg, 73%), mp 87-89' (lit.4 mp 91-93O). Anal. Calcd for C&N02: C, 65.31; H, 3.43; N, 9.52. Found C, 65.16; H, 3.46; N, 9.66.B. From Piperonaldoxime Prepared in Situ. A mixture of hydroxylamine hydrochloride (462 mg, 6.5 mmol), sodium methoxide (350 mg, 6.5 mmol), and 20 ml of MezSO was stirred at room temperature for 15 min. Piperonal (1 g, 6.5 mmol) was added and the mixture was heated at 70' for 2 hr. Heating was then discontinued, p-nitrobenzonitrile (980 mg, 6.5 mmol) and freshly ground potassium hydroxide (758 mg, 13 mmol) were added, and the mixture was stirred at room temperature for 3-4 hr. Work-up as in part A and recrystallization from ethanol-water afforded 742 mg (78%) of piperonylonitrile, mp 87-891° (lit.4 mp 92-93').Yavari, Esfandiari, Mostashari, and Hunter Chem.When benzofurazan is irradiated by ultraviolet light (3000 A), a reactive nitrile oxide intermediate is produced.In order to trap this intermediate, benzofurazan has been irradiated in dimethyl acetylenedicarboxylate (DAD).The nitrile oxide reacts with DAD to produce various geometrical isomers of dimethyl 3-(4-cyanobuta-l,3-dienyl)isoxazole-4,5-dicarboxylate (8). The isoxazoles have been characterized by their NMR spectra. All the isomers have been degraded to the same dimethyl 3-carboxaldehydeisoxazole-4,5-dicarboxylate (9) by ozonolysis. Cis,cis, trans,cis, and trans,trans isomers of 8 have been identified.

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Section: Methodsmentioning

confidence: 99%

Photoreaction of benzofurazan and dimethyl Acetylenedicarboxylate. Synthesis of isomeric isoxazoles. Carbon-13 nuclear magnetic resonance spectra of isoxazoles and oxazoles

Yavari¹,

Esfandiari²,

Mostashari³

et al. 1975

J. Org. Chem.

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“…One of the first examples ( Scheme 25 ) is from Fournier and Miller [ 61 ], who used 2-(4,5-dibenzoyl-1 H -1,2,3-triazol-1-ylmethyl)-3,4,6-trimethylhydroquinone diacetate and hydrazine hydrate in ethanol to form 4,5-diphenyl-1 H- 1,2,3-triazolo[4,5- d ]pyridazine. In a comparable manner, Erichomovitch [ 62 ] used triazole diesters 94 to obtain diacylhydrazides 95 , which were heated to form 1 H- 1,2,3-triazolo[4,5- d ]pyridazines 96 in 80% yield with loss of hydrazine.…”

Section: Synthetic Approachesmentioning

confidence: 99%

Syntheses and Applications of 1,2,3-Triazole-Fused Pyrazines and Pyridazines

Hoffman

Schoffstall

2022

Molecules

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Pyrazines and pyridazines fused to 1,2,3-triazoles comprise a set of heterocycles obtained through a variety of synthetic routes. Two typical modes of constructing these heterocyclic ring systems are cyclizing a heterocyclic diamine with a nitrite or reacting hydrazine hydrate with dicarbonyl 1,2,3-triazoles. Several unique methods are known, particularly for the synthesis of 1,2,3-triazolo[1,5-a]pyrazines and their benzo-fused quinoxaline and quinoxalinone-containing analogs. Recent applications detail the use of these heterocycles in medicinal chemistry (c-Met inhibition or GABAA modulating activity) as fluorescent probes and as structural units of polymers.

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“…15 It occurred to us that in these compounds the presence of an electron-withdrawing group at 4-position of the isoxazole ring would not only provide a fast reacting substrate for Baylis-Hillman reaction but also would lead to a scaffold to construct 5,8-dihydro-isoxazole [4,5-c]azepine-4-one, a novel isoxazole-annulated ring system. The scanning of literature does not reveal the synthesis of this heterocyclic system though various other ring systems including benzoxepino, 16 pyridazine, 17 pyrazine, 18 pyrrole, 19 pyrimidine, 20 triazole 21 annulated to isoxazole have been reported. As was expected, the Baylis-Hillman reaction of 3-aryl-5-formylisoxazole-4-carboxylate was found to be unusually fast and the resulting product did provide the scaffold for the synthesis of 5,8-dihydroisoxazolo [4,5c]azepin-4-one, a new isoxazole annulated heterocyclic system.…”

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confidence: 94%

Baylis-Hillman Reaction Assisted Synthesis of Substituted 5,8-Dihydroisoxazolo[4,5-c]azepin-4-ones: A Novel Isoxazole-Annulated Heterocycle

Batra¹,

Roy²

2004

Synthesis

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The novel synthesis of a new isoxazole-annulated heterocycle namely, 5,8-dihydroisoxazolo[4,5-c]azepin-4-one, described herein is based on the reaction of benzylamine with acetates of Baylis-Hillman adducts generated from 3-aryl-5-formyl-isoxazole-4-carboxylate.The Baylis-Hillman reaction is extremely useful in furnishing products of high functional density and it has been extensively applied to achieve the synthesis of heterocycles and benzannulated compounds. 2,3 These compounds have been obtained either directly as products of BaylisHillman reaction or by appropriate modification of derivatives of the Baylis-Hillman adducts. [2][3][4][5][6][7][8][9][10][11] Our research efforts are concerned with the exploration of the Baylis-Hillman reaction of substituted isoxazolecarbaldehydes and the synthetic utility of the resulting products. [12][13][14] In this context we have recently reported the synthesis of 5-aryl-3-formylisoxazole-4-carboxylate. 15 It occurred to us that in these compounds the presence of an electron-withdrawing group at 4-position of the isoxazole ring would not only provide a fast reacting substrate for Baylis-Hillman reaction but also would lead to a scaffold to construct 5,8-dihydro-isoxazole[4,5-c]azepine-4-one, a novel isoxazole-annulated ring system. The scanning of literature does not reveal the synthesis of this heterocyclic system though various other ring systems including benzoxepino, 16 pyridazine, 17 pyrazine, 18 pyrrole, 19 pyrimidine, 20 triazole 21 annulated to isoxazole have been reported. As was expected, the Baylis-Hillman reaction of 3-aryl-5-formylisoxazole-4-carboxylate was found to be unusually fast and the resulting product did provide the scaffold for the synthesis of 5,8-dihydroisoxazolo[4,5-c]azepin-4-one, a new isoxazole annulated heterocyclic system. The details of our preliminary investigations are presented here.The Baylis-Hillman reaction of 3-aryl-5-formyl-4-isoxazolecarboxylate 1a-c with activated alkenes without any solvent was significantly fast to afford the corresponding Baylis-Hillman adducts 2-6 along with the unidentified polar impurities as major product. After a series of optimization studies for ascertaining the optimum reaction condition to achieve best yields of products, the anhydrous conditions using dry THF was found to be the most suitable. Though this reaction condition furnished the BaylisHillman adduct in excellent yields with methyl, ethyl and butyl acrylates, only moderate yield could be achieved with tert-butyl acrylate (Scheme 1). It will be appropriate to mention here that the presence of moisture during the Baylis--Hillman reaction of these substrates significantly reduced the yield of the products. It was envisaged that the reaction of primary amine with the acetate of the BaylisHillman adducts followed by subsequent intramolecular cyclization involving ester on the isoxazole nucleus and the NH groups could furnish the desired isoxazole-annulated ring system. However, this optimistic presumption was based on considerations that Z stereoc...

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La Synthèse De Quelques Nouvelles Pyridazines Bicycliques

Abstract: not available

Cited by 19 publications

References 0 publications

Photoreaction of benzofurazan and dimethyl Acetylenedicarboxylate. Synthesis of isomeric isoxazoles. Carbon-13 nuclear magnetic resonance spectra of isoxazoles and oxazoles

Photoreaction of benzofurazan and dimethyl Acetylenedicarboxylate. Synthesis of isomeric isoxazoles. Carbon-13 nuclear magnetic resonance spectra of isoxazoles and oxazoles

Syntheses and Applications of 1,2,3-Triazole-Fused Pyrazines and Pyridazines

Baylis-Hillman Reaction Assisted Synthesis of Substituted 5,8-Dihydroisoxazolo[4,5-c]azepin-4-ones: A Novel Isoxazole-Annulated Heterocycle

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