Mohamed Abdel-Megid

Reactivity of Functionally Substituted Azoles Towards Electrophiles. Novel Synthesis of Thienylazoles and Phenylazoles

Abstract Phenacyl bromide reacted with imidazole 1a and 1,2,4-triazole 1b to yield the respective azolylacetophenones 1c,d. These reacted with phenyl isothiocyanate and phenacyl bromide yielding thienylazoles 4a,b. Reaction of 1c,d with dimethylformamide dimethylacetal followed by treating of the product with thiourea afforded the azolylpyrimidines 10a,b. Azolylpyrans 8a,b were obtained from reaction of 1c,d with acrylonitrile. The reaction of azoles 1a,b with chloroacetylacetone in acetone solution in the presence of base afforded the phenylazoles 13a,b.

A New Route for the Synthesis of Substituted Pyridazines

Abstract Condensation of 4‐acetyl‐5,6‐diphenyl‐2,3‐dihydropyridzin‐3‐one (1) with dimethylformamide dimethylacctal (DMFDMA) afforded the enaminone 2. This could be converted into the pyrazolylpyridazine derivative 4 on reaction with hydrazine hydrate and into pyridazinylpyridazinone 7a,b via coupling with aromatic diazonium salts and subsequent treatment with active methylene compounds. The reaction of 6 with dimethyl acetylenedicarboxylate in the presence of triphenylphosphine afforded the pyridazinylpyridazine derivative 8. Compound 1 converted into 9 upon reflux in acetic acid in the presence of ammonium acetate and afforded 10 on reflux in acetic acid.

Substituted Quinolinones, Part 12: Heterocyclization Reactions of 3‐(3‐Chromonyl)acryloylquinolinone with Some Bifunctional Nucleophiles

Abstract 4‐Hydroxy‐1‐methyl‐3‐[E‐3‐(4‐oxo‐4H‐chromen‐3‐yl)acryloyl]quinolin‐2(1H)‐one (3) was smoothly obtained via a one‐pot aldol dehydration reaction of 3‐acetyl‐4‐hydroxyquinolin‐2(1H)‐one with 3‐formylchromone and was utilized to prepare miscellaneous triheterocyclic systems containing the quinolinone moiety. Both the α,β‐unsaturated ketone side chain and the γ‐pyrone ring in compound 3 were subjected to nucleophilic cyclization with certain 1,2‐ and 1,3‐bifunctional N,N‐, N,O‐, N,C‐, and O,C‐nucleophiles under different reaction conditions. Many pyrazolinyl‐, isoxazolinyl‐, pyrimidinyl‐, and pyridinylquinolinones bearing other six‐ or five‐membered heterocyclic systems have been conveniently synthesized using more than one synthetic route. Dedicated to the memory of the late Professor Sayed Ibrahim El‐Nagdi.

SYNTHESIS OF SOME NEW PYRIDAZINYLSPIROHETARYLINDOLES AND HETARYLPYRIDAZINE DERIVATIVES

Condensation of 4-acetyl-5,6-diphenylpyridazine-3(2H)-one (1) with 1H-indol-2,3-dione afforded the biheterocyclic enone 2. Interaction of 2 with some bifunctional nitrogen nucleophiles and dimedone yielded some novel pyridazinyl spirohetarylindoles 3-6. The reaction of 3-chloropyridazine derivative 7 with some heterocyclic compounds having vicinal amino and cyano groups gave hetarylaminopyridazines 9 and 13. Treatment of acetylpyridazinone 1 with arylidenecyanoacetate and arylidenemalononitrile afforded pyridylpyridazines 16 and 19, respectively. The effect of some active methylene compounds and thioacetamide on biheterocyclic enone 22 was also studied.

Synthesis, Characterization and ِAntimicrobial Activities of Some New Heterocyclic Schiff Bases Derived from Thiocarbohydrazide

The reaction of prazolobenzothienopyrimidine-3-carbaldehyde 1 with thiocarbohydrazide afforded the Schiffs base 3. The latter compound reacted with some electrophilic reagents to give 1,2,4-triazoles 4-6 and 1,2,4-triazines 7-9. Treatment of compound 3 with 2-cyano-3,3-bis(methylthio)acrylonitrile gave the corresponding 5-amino-4-cyano-3-methylthiopyrazole derivative 11. The reaction of pyrazole 11 with carbon disulfide afforded dithioxopyrazolopyrimidine 12. Acylation of compound 11 by using acetic anhydride yielded acetamide 13. On the other hand, the cyclocondensation of pyrazole 11 with acetic anhydride in pyridine yielded pyrazolopyrimidine derivative 14. The reactivity of compound 11 towards formamide and phenylisothiocyanate to give the pyrazolopyrimidines 15 and 16 was studied. The newly synthesized compounds were screened for their antimicrobial activity.