SYNTHESIS OF NEW POLYFUNCTIONALLY SUBSTITUTED PYRIDAZINES, PHTHALAZINES, CINNOLINES AND THIENO[3,4-c]PYRIDAZINES (original) (raw)
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ChemInform, 2003
Condensation of 4-cyano-5,6-dimethyl-3-pyridazinone 1 with aromatic aldehydes gave the novel styryl derivatives 2a-c. Refluxing of compound 2a with phosphorus oxychloride furnished 3-chloropyridazine derivative 3. Compound 3 was reacted with thiourea and produced pyridazine-3(2H)thione 4. Thieno[2,3-c]pyridazines 5a-e were achieved by cycloalkylation of compound 4 with halocompounds in methanol under reflux and in the presence of sodium methoxide. Also, refluxing of compound 4 with N-substituted chloroacetamide in the presence of potassium carbonate afforded thienopyridazines 6a-e. Cyclization of compound 6 with some electrophilic reagents as carbon disulfide and triethyl orthoformate furnished the novel pyrimido[4',5':4,5]thieno[2,3-c]pyridazines 12 and 13a-c, respectively. Diazotisation of compound 6 with sodium nitrite in acetic acid produced the pyridazino[4',3':4,5]thieno[3,2-d][1,2,3]triazines 14a-c. Ternary condensation of compound 1, aromatic aldehydes and malononitrile in ethanol containing piperidine under reflux afforded the novel phthalazines 16a-c. Compound 3 was subjected to some nucleophilic substitution reactions with amines and sodium azide and formed the aminopyridazines 17a, b and tetrazolo[1,5-b]pyridazine 19, respectively. The structures of the synthesized compounds were established by elemental and spectral analyses.
Tetrahedron, 2013
We hereby report the synthesis of a novel class of compounds, 7-aminofuro-and 7-aminothieno[2,3-d] pyridazin-4(5H)-one and 4-aminophthalazin-1(2H)-ones starting from methyl 2-(2-methoxy-2oxoethyl)furan-and thiophene-3-carboxylate and methyl 2-(2-methoxy-2-oxoethyl)benzoate. The ester functionalities connected directly to the aromatic ring were regiospecifically converted to the acid, whereas methylene groups were oxidized to the corresponding ketoesters. Reaction of the ketoesters with hydrazine provided the hydrazone derivatives. An intramolecular cyclization in the presence of thionyl chloride formed a fused pyridazinone skeleton. Hydrolysis of the remaining ester groups and transformation of the acid functionalities to the acyl azides followed by Curtius rearrangement gave the isocyanates. Reaction of the isocyanates with methanol and water produced urethane and aminopyridazinone derivatives, respectively.
Synthesis of some new hetarylpyranopyridazines, cinnolines, and hetarylpyridazine derivatives
Chemistry of …, 2009
4-Acetyl-5,6-diphenylpyridazin-3(2H)-one was condensed with 6-chloro-3-formylchromone under different reaction conditions to yield the enone or pyranopyridazine. Both compounds were used in the synthesis of some new hetarylpyranopyridazines. Pyranodipyridazine was obtained via a sequence of reactions of 4-acetyl-5,6-diphenylpyridazin-3(2H)-one with diethyl carbonate, acetic anhydride, and 4-bromobenzenediazonium chloride. The reactions of pyridazinylbutane-1,3-dione with conc. H 2 SO 4 , POCl 3 , hydrazines, hydroxylamine hydrochloride, cyanoacetamide, thiourea, and thiosemicarbazone were also studied.
Arkivoc, 2009
Several new pyrido[4,3-d]pyrimidine, pyrimido[4,5-d]pyridazine and thiazolo[3,4-c]pyrimidine derivatives were prepared from the versatile, readily accessible ethyl 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate. Bromination of the latter compound afforded the corresponding 6-bromomethylpyrimidine derivative. Treatment of the latter with malononitrile or ethyl cyanoacetate afforded the corresponding hexahydrocyclopenta[d]pyrimidine derivatives 4a,b. Reaction of the bromomethylpyrimidine with potassium cyanide followed by treatment with arenediazonium salt afforded the corresponding hydrazone 6 which reacts with hydrazine derivatives to afford the corresponding pyrido[4,3-d]pyrimidine derivatives 8a,b. It reacts also with thiourea, thiosemicarbazide and phenylhydrazine to afford ethyl 3-imino-5-oxo-7-phenyl-3,5,6,7-tetrahydro-1-H-thiazolo[4,3-c]pyrimidine-8-carboxylate (10a), ethyl 3-hydrazono-5-oxo-7-phenyl-3,5,6,7-tetrahydro-1-H-thiazolo[3,4-c]pyrimidine-8-carboxylate (10b) and 4,6diphenyl-3,4,7,8-tetrahydropyrimido[4,5-d]pyridazine-2,5-(1H,6H)-dione (12), respectively. The antimicrobial activity of selected examples of the synthesized compounds was tested and showed moderate activity.
Tetrahedron, 1995
The pyridaziuyl-5carhonitriles (3a-d) were prepared via condensing the aryl hydrazones 2a-d with ethyl cyanoacetate. Similar condensation of Za with malononitrile gives the pyrido[2,3-clpyridazine derivative (8). Compounds 3ad reacted with elemental sulphur i n refluxing ethauolic solutions in the presence of triethylamine to yield the thieno[3,4-dlpyridazinones 9a-d. The 1.3.4~thiadiazaacenaphthene 12 was prepared via reacting 9e with diethyl fumarate. In contrast, only the phthalazines 14a-c were produced from tbe reaction of 13a-c with 9e. Compounds 9a-c reacted with acrylonimle to yield the 1,3.4-thiadiazaacenaphthenes 18a, b. Compound 3a condensed with benzaldehyde to yield 19a. Condensation of 3~. e, d with dimethylformamide dimethylacetal afforded 19b-d. Compound 19b cyclized into 20b when refluxed in acetic acid iu the presence of ammonium acetate. lliis same product was obtained from the reaction of the amide 38 with formaldehyde in refluxiug pyridine. The reaction Of 3a, c with arylidenemalononitrile (23a, b) gives the tetrabydrophthalazines 2%~. The pyridazin-4-ones 26a-d were prepared from the reaction of 2a-d with dimethylformamide dimethylacetal in refluxing dioxane. The crystal and molecular structure of compound 18a was solved by X-ray analysis.
Synthesis and reactions of 5-phenylpyrido-[3,2-d]-pyridazin-8(7H)-one derivatives
2013
Reaction of picolinic acid anhydride with dry benzene under Friedl-Crafts conditions gave 3-benzoyl picolinic acid 1 which on reaction with hydrazine hydrate in boiling n- butanol afforded 5-phenylpyrido[3,2-d]pyridazine-8(7H)-one 2. Reaction of pyridazinone 2 with ethyl chloroacetate in dry acetone and K2CO3 gave ethyl 2-( 5-phenylpyrido[3,2- d]pyridazin—8-yloxyl)acetate 3 which on reaction with hydrazine hydrate in refluxing ethanol afforded 2-( 5- phenylpyrido [3,2-d]pyridazin—8-yloxyl)acetohyrazide 4 .Cyclization of the acid hydrazide 4 with phenyl isothiocyante under different conditions afforded oxadiazole and thiadiazole derivatives 9 and 10. Also, cyclization the acid hydrazide 4 with of CS2 in alcoholic KOH and with benzoic acid in refluxing with POCl3 gave oxadiazole derivatives 12 and 13 respectively . Hydrazones 14a,b and c were prepared via the reaction of the acid hydrazide 4 with appropriate aldehydes flowed by treatment with thioglycolic acid gave thiazolidine 15a,b ...