Synthesis, structural characterization and antimicrobial evaluation of some novel piperidin-4-one oxime esters

Fifteen novel biologically active piperidin-4-one oxime esters 8-22 were synthesized in good yields. These compounds were prepared in reactions of carboxylic acids, in situ activated using POCl3 and pyridine, with piperidin-4-one oximes. The structures of the title compounds were elucidated based on FTIR, NMR (1D and 2D) and mass spectral analyses. Single crystal XRD studies of compounds 12 and 20 provided further unambiguous evidence for the proposed structure. All the synthesized compounds were tested for their in vitro antibacterial and antifungal activities. Many of these derivatives exhibited good activity against Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, Trichoderma viride and Aspergillus flavus.