Benzo[4’,5’]imidazo[2’,1’:6,1]pyrido[2,3-d]pyrimidines: Past and Present

Synthetic approaches to the construction of the heterocyclic benzo[4’,5’]imidazo[2’,1’:6,1]pyrido[2,3-d]pyrimidine system based on heterocyclizations of substituted benzimidazoles and a new alternative strategy based on 2,4,6-trisubstituted pyrimidinyl-5-propanoic acids are considered. The latter method has been shown to be a successful addition to previously described methods, since it allows one to bypass the significant limitations associated with the use of substituted benzimidazoles and allows the introduction of functional substituents at different positions of the heterocycle that are inaccessible by other methods. The available information on derivatives of this heterocyclic system and their biological properties is summarized.