Synthesis of Isoxazolo and Pyrazolino Annelated Carbazoles from 2-(4'-Methoxy)benzylidene-1-oxo-1,2,3,4-tetrahydrocarbazoles

Abstract

1-Oxo-1,2,3,4-tetrahydrocarbazole (1) on mixed aldol condensation with 4-methoxybenzaldehyde yielded 2-(4'-methoxy)benzylidine-1-oxo-1,2,3,4-tetrahydrocarbazole (2), which was further treated with hydrazine hydrate and hydroxylamine hydrochloride in separate reactions to afford 3,3a,4,5-tetrahydro-3-(4'-methoxy)-phenyl-2H-pyrazolino[3,4-a]carbazole (3) and 4,5-dihydro-3-(4'-methoxy)phenylisoxazolo[3,4-a]carbazole (4). The prepared compounds 3a–e and 4a–e were evaluated for their in vitro antibacterial and antifungal activities against certain pathogenic fungal and bacterial strains.