A series of poly(phenylene)vinylene (PPV) derivatives with different geometries and peripheral functional groups have been synthesized by Horner‐Wadsworth‐Emmons reaction. Compounds bearing carboxylic acid or quaternary ammonium functional groups prepared by this metal‐free protocol were weakly active against both Gram‐negative and Gram‐positive bacteria, which is in contrast to previously reported results. The activity of polyanionic derivatives was higher for Gram‐negative bacteria and showed bacteriostatic behavior, whereas polycationic derivatives were clearly more active against Gram‐positive bacteria and behaved as bactericidal agents. The spatial disposition of the active groups seems to play a key role, with the highest activity observed for a C3v geometry. The presence of quaternary ammonium functional groups also facilitated the internalization of the molecules into the bacteria. Levels of cytotoxicity similar to that of the solvent were obtained for most compounds against COS‐1 and VERO cells.

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Using rescaffolding approach, we designed piperidine compounds decorated with an electrophilic oxathiazol-2-one moiety that is known to confer selectivity towards threonine proteases. Our efforts to prepare products according to the published procedures were not successful. Furthermore we identified major side products containing nitrile functional group, resulting from carboxamide dehydration. We systematically optimized reaction conditions towards our desired products to identify heating of carboxamides with chlorocarbonylsulfenyl chloride and sodium carbonate as base in dioxane at 100 °C. Our efforts culminated in the preparation of a small series of piperidin-3-yl-oxathiazol-2-ones that are suitable for further biological evaluation.

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