Ali Deeb

Pyridazine Derivatives and Related Compounds, Part 17: 1 The Synthesis of Some 3-Substituted Pyridazino[3′, 4′:3, 4]pyrazolo[5, 1-c]-1,2,4-triazines and Their Antimicrobial Activity

The reaction of the hydrazide of pyridazino[3′, 4′:3, 4]pyrazolo[5, 1-c]-1,2,4-triazine-3-carboxylic acid 3 with carbon disulfide in the presence of potassium hydroxide gave the 1,3,4-oxadiazole-2-thione derivative 4. The methylation of this product in an alkaline medium proceeds at the sulfur atom. The reaction of 3 with KOH and carbon disulfide followed by addition of hydrazine hydrate afforded the 4-amino-1,2,4-triazole derivative 6. Compound 3, when heated either with ammonium thiocyanate or with potassium thiocyanate, afforded the same product 7, which underwent cyclodehydration in the presence of acetyl chloride, which led to the 2-acetylamino-1,3,4-thiadiazole derivative 8. In a basic medium, the product was 1,2,4-triazole-3-thione derivative 9. The reaction of 3 with phenyl isothiocyanate provided thiosemicarbazide derivative 10, which underwent cyclodehydration in a basic medium and gave the 1,2,4-triazole derivative 11. The reaction of 3 with formic acid yielded the 3-carboxyl-2′-(formyl)hydrazine derivative 12. The refluxing of the latter with phosphorus pentasulfide in xylene yielded compound 14 (65%). The reaction of compound 12 with phosphorus pentoxide afforded compound 15. Some representative examples were screened for antimicrobial activity.

Pyridazine Derivative and Related Compound, Part 18:1 Pyridazino [3′,4′:3,4]pyrazolo [5,1-c]-1,2,4-triazine-3-carboxylic Acid: Synthesis, Reactions, and Antimicrobial Activity

A series of 3-substituted pyridazino[3′,4′:3,4]pyrazolo[5,1-c]-1,2,4-triazens have been synthesized starting from the 3-carboxylic acid derivative 2. The reaction of the acid chloride 3 with amines gave the corresponding anilides 4. The reaction of 2 with ethyl chloroformate and sodium azide in the presence of triethyl amine gave the carbonyl azide 5, which underwent a Curtius rearrangement in boiling ethanol to afford the carbamate 6, which converted to the 3-amino derivative 7 upon alkaline hydrolysis, and the reaction with acid chloride resulted in N-substituted products 9. On other hand, the reaction of the carboxylic acid 2 with POCl3 and thiosemicarbazide afforded 2-amino-1,3,4-thiadiazole derivative 13. The condensation of 13 with aldehydes furnished 14 in a good yield. The products were screened for their antimicrobial activity against six microorganisms.

Pyridazine Derivatives and Related Compounds Part 24. 1 Synthesis and Antimicrobial Activity of Some Sulfamoylpyrazolo[3,4-c]pyridazine Derivatives

A series of new sulfamoylpyrazolo[3,4-c]pyridazine derivatives was synthesized. Some of these compounds show interesting antimicrobial activity.

Pyridazine derivatives and related compounds, Part 12: Synthesis of some pyridazino [4',3':4,5]thieno[3,2-d]-1,2,3-triazines

Abstract The syntheses of pyridazino[4′,3′:4,5]thieno[3,2−d]-1,2,3-triazinones 2, 3, 6, derivatives of the ring system thieno[2,3-c]pyridazine, have been accomplished by a diazotization reaction. Reaction of triazine 3 with phosphorous oxychloride led to 4-chloro derivative 7 which, on further displacement reactions, gives 4-substituted derivatives. All new compounds were characterized by elemental analyses and spectral data.

Pyridazine and its related compounds. Part 36. Synthesis and antimicrobial activity of some novel pyrimido[4′,5′:4,5]thieno[2,3-c]pyridazine derivatives

Novel derivatives of pyrimidothienopyridazine were designed and synthesized through a versatile method. Some of the target compounds bearing the sulfonamide group were evaluated for their antimicrobial activity against representative Gram-positive bacteria, Gram-negative bacteria, and fungi by applying the agar plate diffusion technique. The results showed that derivatives 11a have promising inhibitory activity against Gram-positive bacteria, and derivatives 11b and 11e have also potent inhibition against fungi. Rest of the compounds showed moderate to low activity against the examined micro-organisms.

Pyridazine Derivatives and Related Compounds, Part 221: Synthesis, Reactions, and Insecticidal Activity of 3-Amino-5,6-diaryl-1H-pyrazolo[3,4-c]pyridazines

Starting with 3-amino-5,6-diaryl-1H-pyrazolo[3,4-c]pyridazine, the syntheses of thiourea derivatives, dithiocarbamates, ethyl carbamate, phosphoranylidene amino, and substituted acetamido derivatives are described. The products were screened for their insecticidal activity against Mucsa, domestica, and Aphid, Macrosiphum pisi. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Pyridazine Derivatives and Related Compounds. Part 11: 1Synthesis of Some Pyrimido[4′,5′:4,5]thieno[2,3-c]pyridazines

3-Substituted pyrimido[4′,5′:4,5]thieno[2,3-c]pyridazine-2,4-di-ones and 3-amino-2-methylpyrimido[4′,5′:4,5]thieno[2,3-c]pyridazine-4-ones were synthesized starting from ethyl 5-aminothieno[2,3-c] pyridazine-6-carboxylate 1. Reaction of amino ester 1with phenyl isothiocyanate affords thiourea derivative 10which undergo further transformation to the related fused heterocyclic systems.

Pyridazine derivatives and related compounds, Part 9. Tetrazolo[1,5-b]pyridazine-8-carbohydrazide synthesis and some reactions

The reaction of the hydrazide of 6,7-diphenyltetrazolo[1,5-b]pyridazine-8-carboxylic acid (3) with aromatic aldehydes gave 8-arylidenecarbohydrazide derivatives. The reaction of 3 with methanesulfonyl chloride, benzenesulfonyl chloride, phenyl and benzyl isothiocyanates afforded the corresponding N-substituted derivatives. The reaction of 3 with potassium ethylxanthate gave 5-(6,7-diphenyltetrazolo[1,5-blpyridazin-8-yl)-1,3,4-oxadiazole-2-thione (7). The alkylation of this product in an alkaline medium proceeds at the sulfur atom, while the aminomethylation and acylation proceed at the nitrogen atom. Compound (3) also reacted with N-aminothiosemicarbazide to give 4-amino-5-(6,7-diphenyl-tetrazolo[1,5-b]pyridazin-8-yl)-1,2,4-triazole-3-thione (11).

Pyridazine Derivatives and Related Compounds, Part 20:1 Synthesis of Different Heterocycles from 5-Aminothieno[2,3-c]pyridazine-6-carbohydrazide

7-substituted 3,4-diphenylpyrimido[4′,5′:4,5]thieno[2,3-c]pyridazines were synthesized starting from 5-amino-3,4-diphenylthieno[2,3-c]pyridazine-6-carbohydrazide (1). Reaction of carbohydrazide 1 with phthalic anhydride afforded 12,13-diphenyl-6H-pyridazino-[3″,4″: 5′,4′]thieno[3′,2′:4,5]pyrimido-[2,1-a]phthalazine-5,6-dione, (6) which underwent further transformation to the related compounds.

Pyridazine derivatives and related compounds. Part 141. Photolysis of 3-diazo-4,5-diphenylpyrazolo[3,4-c]pyridazine

The photochemistry of 3-diazopyrazolopyridazine has been investigated. The irradiation of 3-diazo-4,5-diphenylpyrazolo[3,4-c]pyridazine in various solvents forms a carbene intermediate, which transforms into 3-substituted derivatives. For photolysis in the presence of acetylacetone or ethyl acetoacetate the coupling reactions which occur at the methylene group are faster than carbene formation, and can lead to direct cyclisation into condensed 1,2,4-triazines. Photolysis in the presence of diethyl malonate forms an acyclic hydrazone.