Synthesis of some benzoxazinyl pyrazolone arylidenes as potent antimicrobials and antioxidants

2-[2-(3-Methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)-2-oxoethyl]-2H-1,4-benzoxazin-3(4H)-one (3) was obtained starting from methyl-(3,4-dihydro-3-oxo-2H-1,4-benzoxazin-2-yl) acetate (1) through the corresponding hydrazide (2). Condensation of (3) with different aromatic aldehydes under Knoevengel condensation afforded 2-{2-[3-methyl-4-(2-methylbenzylidine)-5-oxo-4,5-dihydro-1H-pyrazol-1-yl]-2-oxoethyl}-2H-1,4-benzoxazin-3(4H)-ones (4a–k). The structures of the compounds were determined by FT-IR, ¹H NMR, ¹³C NMR, mass spectral data, and elemental analysis. All the synthesized compounds were screened for their in vitro antimicrobial and antioxidant studies.