Der Pharma Chemica
Journal for Medicinal Chemistry, Pharmaceutical Chemistry, Pharmaceutical Sciences and Computational Chemistry


Synthesis and reactions of oxadiazolo, thiadiazolo and triazolo phthalazin-1(2H)-one derivatives

Author(s): Fathy A. Yassin, Amal F. Seleim

Reaction 2-{2,3-dichlorophenylcarbonyl}-benzoic acid 1 with hydroxylamine hydrochloride in boiling pyridine afforded 4-(2,3dichlorophenyl)-1H-2,3-benzoxazin-1-one 2 which on condensation with ethyl glycinate in the presence of sodium acetate gave ethyl[ 4-(2,3-dichlorophenyl)-1-oxophthalazin-2(1H)-yl)]acetate 3. The sulphonamide derivative 5 was prepared via the reaction of acid hydrazide 4 with p- toluene sulfonyl chloride in refluxing glacial acetic acid. Also, oxadiazole 6 was preformed through the reaction of the acid hydrazide 4 with ethyl chloroformate under reflux in nbutanol. N-amino 4-(2, 3-dichlorophenyl)-2-[5-oxo-4, 5-dihydro1, 3, 4-triazol-2-yl) methyl] phthalazin-1-(2H)-one 7 was prepared via condensation of oxadiazole 6 with hydrazine hydrate in boiling n-butanol. Thiadiazole drevative 10 was prepared by stirring the dithiacarbazate 8 with conc. H2SO4 at room temperature while on refluxing 8 in absolute ethanol afforded the oxadiazole 11. Each of 8, 10 and 11 on hydrazinolysis with hydrazine hydrate gave 2-(4-amino 5-thioxo-4, 5- dihydro-1H-1, 2, 4-triazol-3-yl) 4-(2, 3 dichlorophenyl)-phthalazin-1-(2H)-one 12. Thiourea derivative 15 was prepared by the reaction of 12 phenyl isothiocyanate in refluxing DMF. The structure of all compounds was confirmed from their correct analytical and spectral data.