Synthesis and Anticholinesterase Activity of Some 2,5-Disubstituted Imidazol-4-ones Derived from the Green Fluorescent Protein Chromophore

2-Phenyl-4-[4-(benzoyloxy)benzylidene]-1,3-oxazol-5(4 H )-ones reacted with hexamethyldisilazane to give, depending on the conditions, 3-aryl-2-benzamidoprop-2-enamides (ethyl acetate, 25°C) or 2-phenyl-5-(hydroxybenzylidene)-3,5-dihydro-4 H -imidazol-4-ones (DMF, 150°C). The synthesized compounds were evaluated for their antiradical and anticholinesterase activities. O -Benzoyl derivatives were found to be inferior to compounds containing an α,β-didehydrotyrosine moiety with respect to antiradical activity, whereas imidazole derivatives generally showed a higher anticholinesterase activity than the corresponding α,β-dide­hydrotyrosine derivatives.