[Synthesis of biosynthetic precursors of red fluorescent proteins' chromophores]

A method for the synthesis of 5-arylidene-3,5-dihydro-4H-imidazol-4-ones, the corresponding chromophore of green fluorescent protein (GFP) with acylaminoalkyl substituents at position 2 of imidazole core have been developed. These structures represent biosynthetic precursors of the chromophores of red fluorescent proteins. The method is based on masking of the dehydrotyrosine fragment with beta-hydroxytyrosine moiety The key stages of the synthesis include peptide coupling of beta-hydroxytyrosine with the N-acetylamino acid of choice, unmasking of dehydrotyrosine by O-acylation with subsequent elimination, and cyclization of the obtained derivatives of 3-acylaminocinnamic acid in basic media.