Simple Efficient Routes for the Preparation of Pyrazoleamines and Pyrazolopyrimidines: Regioselectivity of Pyrazoleamines Reactions with Bidentate Reagents

Simple and efficient routes for the preparation of 2-amino-5-phenyl-4,5-dihydrofuran-3-carbonitrile (12), 2-oxo-5-phenyl-tetrahydrofuran-3-carbonitrile (13) and the 3,5-diaminopyrazole derivative 2h were developed. The results of the reactivity profiles of 12 and 2h are reported and the previously investigated reaction of pyrazole-3,5-diamine (2b) with acrylonitrile to yield compound (31), a N-1 acylation product, is currently justified by using X-ray crystallographic analysis. Taken together, the observation of alkenes and alkynes substitution when reacting with 3,5-diaminopyrazole derivative 2h is explained by the terminal electron withdrawing group. This pattern of substitution is attributed to involvement of sterically unhindered electrophiles primarily at the N-1 position. This work is licensed under a Creative Commons Attribution 4.0 International License

A facile synthesis of some biologically active disperse dyes derived from arylazonicotinates and their application on polyester fabrics

A series of 2-hydroxy- and 2-amino-6-substituted-5-arylazonicotinates monoazo disperse dyes 6 and 8a-d were prepared via condensation of 3-oxo-3-substituted-2-arylhydrazonals 1a-d with active methylene nitriles 2a,b. A high temperature dyeing method was employed to apply these disperse dyes for polyester fabrics. Fastness properties of the dyed samples were measured. Most of the dyed fabrics tested displayed very good fastness level to washing, perspiration and light. Finally, the biological activities of the prepared dyes against gram positive and gram negative bacteria were evaluated

Arylazoazines and arylazoazoles as interesting disperse dyes: Recent developments with emphasis on our contribution laboratory outcomes

In this review, we report a survey on the synthesis and application of arylazoazines and arylazoazoles as versatile disperse dyes. Recent reports on the synthesis of arylazonicotinates via condensing arylhydrazonals with active methylene nitriles in acetic acid in presence of ammonium acetate is surveyed. The scope and limitations of this synthetic approach which in some cases afford pyridazinones or arylazonicotinates is defined. Microwave assisted as well as ultra sound assisted synthesis of arylazopyridones as established marketed dyes is also surveyed. Conversion of these arylazopyridones into arylazothienopyridones that can de converted into arylazoisoquinoline derivatives is discussed. Synthesis of arylazopyrazoles and pyrazolopyrimidines via microwave or ultra sound is discussed. The utility of the synthesized compounds as well as antimicrobial disperse dyes and efforts to define their potentialities are also covered

Multicomponent reactions under increased pressure: on the reaction of arylhydrazonals, aromatic aldehydes and malononitrile in Q-Tube

A novel multi-component reaction between arylhydrazonals, malononitrile and aromatic aldehydes under high pressure utilizing Q-tube was carried out. The reaction of arylhydrazonal (1j) with malononitrile and aromatic aldehydes afforded the corresponding biphenyl derivatives (4). However, compound 1h reacted with malononitrile and aromatic aldehydes (7) to afford pyridazino[5,4,3-de]1,6-naphthyridine-7-carbonitrile derivatives (8). In contrast, the arylhydrazonal (1k) at the same reaction conditions afforded the corresponding pyridazinoquinazoline derivative (22). A rationalization for the difference in behavior for reaction of compounds 1h-k with malononitrile and aromatic aldehydes was postulated. Based on these findings a mechanism to account for the formation of the reaction products is suggested excluding possible initial dimerization of malononitrile as has been previously reported

Cerium (IV) ammonium nitrate-mediated reactions: Simple route to benzimidazole derivatives

AbstractThe reaction of o-phenylenediamine with aromatic aldehydes in MeOH at room temperature catalyzed by cerium (IV) ammonium nitrate (CAN) afforded either 2-aryl-1-arylmethyl-1H-benz-imidazoles and/or 2-aryl-substituted benzimidazoles

Studies with Azinylacetonitriles: 2-Pyridylacetonitrile as a Precursor to Functionally Substituted Pyridines

2-Pyridylacetonitrile (1) couples with aromatic diazonium salts to yield arylhydrazones 2a-c, that were shown to exist in the syn-form 2 rather than the anti-form 4. Compounds 2a,c reacted with hydroxylamine in refluxing DMF to yield the interesting 1,2,3-triazolylpyridines 6. Attempts to cyclize 2 to give the corresponding fused pyrazolopyridines 9 failed. On the other hand, compound 1 condensed with dimethylformamide dimethyl acetal to yield enaminonitrile 10 that could be converted into pyrazolylpyridine 11

Studies with Azinylacetonitriles: 2-Pyridylacetonitrile as a Precursor to Functionally Substituted Pyridines

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On the reaction of phenacylmalononitrile with hydrazines: A new route to pyrazolo[3,4-c]pyridazine, isoxazolo[5,4-c]pyridazine and pyrimido[4,5-c]pyridazine

AbstractThe reaction of arylmalononitiles 1a,b with hydrazine hydrate at room temperature has afforded 3-oxo-6-aryl-2,3,4,5-tetrahydropyridazine-4-carbonitrile 3a,b as the sole isolable product. These 3-oxopyridazin-4-carbonitriles underwent aromatization to 3-oxo-6-phenylpyridazine-4-carbonitrile 4 on attempted coupling with benzene diazonium chloride. Compound 3a reacted with hydrazine hydrate as well as urea to yield pyrazolo[3,4-c]pyridazine 5 and pyrimido[4,5-c]pyridazine 6. On the other hand, amidoximes 7a,b were isolated from reaction of 3a,b with hydroxylamine hydrochloride. Amidoximes 7a could be cyclized successfully into 5-phenylisoxazolo[5,4-c]pyridazin-3-amine 8 while 7b could not be cyclized on our hand

Enaminones as Building Blocks in Heterocyclic Syntheses: Reinvestigating the Product Structures of Enaminones with Malononitrile. A Novel Route to 6-Substituted-3-Oxo-2,3-Dihydropyridazine-4-Carboxylic Acids

The reported structures of reaction products of enaminones with malononitrile in ethanolic piperidine are revised. A novel route to 2,3-dihydropyridazine-4-carboxylic acids 4a-c via reactions of 2-cyano-5-(dimethylamino)-5-arylpenta-2,4-dienamides 8a-c with nitrous acid or with benzenediazonium chloride is reported. Compounds 8a-c are converted to 1,2-dihydropyridine-3-carboxylic acid and 1,2-dihydropyridine-3-carbonitrile derivatives upon reflux in EtOH/ HCl and in AcOH