[Synthesis of the chromophores of fluorescent proteins and their analogs].

Members of the green fluorescent protein (GFP) family are widely used in experimental biology as genetically encoded fluorescent tags. Chromophores of GFP-like proteins share a common structural core: 3,5-dihydro-4H-imidazol-4-one. This review covers synthetic approaches to 3,5-dihydro-4H-imidazol-4-ones, substituted at different positions. General, as well as specific methods, represented by single examples are considered. The most popular synthetic route to substituted 3,5-dihydro-4H-imidazol-4-ones includes synthesis of azlactones, followed by transformation into N-acyldehydroaminoacids and, finally, cyclization into target heterocycles. Accordingly, the review is divided into three parts: the first part covers syntheses of azlactones, the second part covers main approaches to N-acyldehydroaminoacids, and in the third part we summarize cyclizations of N-acyldehydroaminoacids, as well as all other approaches to 3,5-dihydro-4H-imidazol-4-ones.