Synthesis and reactions of some novel 4-biphenyl-4-(2H)-phthalazin-1-one derivatives with an expected antimicrobial activity

In this study reaction of 1-(biphenyl-4-carbonyl)benzoic acid (1) with hydrazine hydrate, phenyl hydrazine, acetyl hydrazine and benzoyl hydrazine in boiling dry benzene gave the corresponding 4-biphenyl-4-yl-(2H)-phthalazin-1-one (2a-d), respectively. The structure of 2c was established via its reaction with 2-chlorobenzaldehyde, 2-nitrobenzaldehyde in ethanol to give the chalcones 3a,b, respectively. On the other hand, the cyclocondensation of the acid 1 with semicarbazide and thiosemicarbazide in sodium acetate gave phthalazinone amide/thioamide 411,b, respectively. The reaction of 1 with hydroxyl amine hydrochloride in different media was also studied, to give the oxime derivative 5, which was readily converted to benzooxazin-1-one derivative 6 by boiling in acetic anhydride. Compound 6 was also obtained, when the acid 1 was reacted with hydroxyl amine hydrochloride in boiling pyridine. In addition, the phthalazinone derivative 2a reacted under Mannich reaction condition with phthalimide, morpholine, o-crezole and beta-naphthol to give Mannich bases 7a-d, respectively. The structural assignment of the new compounds was based on analytical and spectral data. And some of the new products showed antimicrobial activity. (C) 2010 King Saud University. All rights reserved.