Synthesis and Biological Screening of 4-Benzyl-2H-phthalazine Derivatives

Abstract

Preparation of 4-benzyl-2-substituted phthalazin-1-one derivatives 2-8 isreported. Condensation of 4-benzyl-1-chlorophthalazine (9) with a series of differentnucleophiles gave 4-benzylphthalazin-1-ylamino derivatives (10-13 and 16) and4-amino-2-[N'-(4-benzylphthalazin-1-yl)-hydrazino]-6-arylpyrimidine-5-carbonitriles (14a,b).Interaction of 9 with ambident anions was also studied. 5-Benzyl-6,6a,12-triazobenzo[a]-anthracen-7-one (15) is obtained from 9 and anthranilic acid derivatives. Treatment of 16with (EtO)3CH/Ac2O under reflux afforded the corresponding ethoxymethylene derivative17, while aqueous ammonium hydroxide treatment afforded carboxamide derivative 18.The structures of the newly synthesized derivatives were confirmed by their elementalanalysis, IR, 1H NMR, 13C NMR and mass spectral studies. Antimicrobial activities ofsome selected compounds were also studied and some of these were found to exhibitpromising effects against Gram-positive and Gram-negative bacteria and fungi. © 2011 by the authors; licensee MDPI, Basel, Switzerland.