Treatment of a mixture of 3-methyl-1-phenylpyrazol-5-one 1 with a diversity of aromatic aldehydes and
piperidine in absolute ethanol (24 h at 0 ºC) gave products in good yields. Biological screening of the synthesized
derivatives for their antimicrobial activity against various bacteria (gram positive and gram negative) as well as against
fungi have been evaluated, where derivatives 3 and 11 were found to be the most potent.
Characterization of all the formed derivatives was emphasized by melting point determination, NMR data in addition to
their mass spectra.