Abstract
The reaction of 3-(1,4-dioxo-3,4-dihydrophthalazin-2(1H)-yl)-3-oxopropanenitrile 1 and salicyladehyde furnished coumarin derivatives 4 and 5. Coupling reaction of 1 with aryl diazonium chlorides and benzene-1,4-bis (diazonium) chloride gave the corresponding hydrazones 6a,b and bishydrazone 9, respectively. Hydrazones 6 underwent intramolecular cyclization upon treating with hydrazine hydrate to give 3-aminopyrazoles 7. Pyranyl phthalazine 13 was prepared from the reaction of 1 with ethyl 2-cyano-3-ethoxyacrylate 10. Enaminonitrile 14 was reacted with hydrazine hydrate/phenylhydrazine and hydroxylamine to afford the corresponding pyrazoles 16 and oxime 17. The antimicrobial evaluation revealed pyrazole derivatives 7a,b and 16a,b displayed a broad spectrum activity against most strains. 3-Aminopyrazole derivative 7b showed potent antibacterial activity against all tested microorganisms.