Synthesis and Reactions of Some New Benzylphthalazin-1-ylaminophenols, 2H-Chromene and 5H-Chromeno[2,3-d]pyrimidine Derivatives with Promising Antimicrobial Activities

A series of (4-benzylphthalazin-1-ylamino)phenols 4-6 were prepared. Bromination of (4-benzylphthalazin-1- ylamino)phenol (1) with bromine afforded the bromophenol derivative 7, while condensation of the isomeric (4- benzylphthalazin-1-ylamino)phenol (2) or 7-(4-benzylphthalazin-1-ylamino)naphthalene-2-ol (3) with arylidenemalononitriles 8a-c in ethanol/piperidine solution afforded chromene derivatives 9a-c and 10a,b. Treatment of 7-(4- benzylphthalazin-1-ylamino)-4-(p-methoxyphenyl)-4H-chromene-3-carbonitrile (9a) with triethyl orthoformate/Ac2O afforded ethoxymethyleneamino derivative 11. Condensation of 9a with DMFDMA/xylene gave chromenopyrimidine derivative 13, while treatment of 9a with Ac2O afforded the N-acetylimino derivative 14. The structures of the newly synthesized derivatives were confirmed by their elemental analysis and spectral data. The antimicrobial activities of some selected compounds were also studied and some of them were found to exhibit promising effects against Gram-positive and Gram-negative bacteria and fungi.