Heterocyclic synthesis via enaminones:: Novel synthesis of (1H)-pyridin-2-one, pyrazolo[1,5-a]pyrimidine and isoxazole derivatives incorporating a N-methylphthalimide and their biological evaluation

Novel synthesis of (1H)-pyridin-2-one, pyrazolo[1,5-alpha]pyrimidine and isoxazole derivatives incorporating N-methylphthatimide moiety are reported. Reaction of enaminone 2 with malononitrile affords 4. Condensation of 2 with cyanothioacetamide or benzoylacetonitrile affords compounds 6 and 7 respectively. Reaction of 2 with hydrazine hydrate afford 2,3-dihydrophthalazine-1,4-dione (10). Condensation of 2 with hydroxylamine and 3-aminopyrazole derivatives affords compounds 12 and 15a,b respectively. Antimicrobial and antifungal activity were determined for representative compounds and most of them showed moderate activity as antimicrobial agents, while compounds 2 and 7 show strong activity against Aspergillus niger. The structure of the newly synthesized compounds was elucidated by elemental analyses and H-1 nmr spectra and some cases by C-13 nmr investigation.