A method for the synthesis of 5-arylidene-3,5-dihydro-4H-imidazol-4-ones corresponding to the chromophore of the green fluorescent protein (GFP) with acylaminoalkyl substituents at position 2 of the imidazolone core has been developed. These biomimetic model compounds are the precursors of the chromophores of red fluorescent proteins. The method is based on the masking of the dehydrotyrosine fragment of target compounds by the β-hydroxytyrosine moiety. The key stages of the synthesis include the condensation of β-hydroxytyrosine with the appropriate N-acetylamino acid, the unmasking of dehydrotyrosine by O-acylation with subsequent elimination, and the cyclization of the resulting 3-acylaminocinnamic acid derivatives in basic medium.
- Green fluorescent protein