Synthesis of 6-substituted 7-aryl-5,6-dihydropyrido[2,3-d]pyrimidine(1H,3H)-2,4-diones using the Vilsmeier reaction

摘要

The reaction of 6-amino-1,3-dimethyluracil with equimolar amounts of arylalkanone Mannich bases under optimized reaction conditions leads to 7-aryl-5,6-dihydropyrido[2,3-dlpyrimidines in a yield of 50-80%. Functionalization of these dihydropyridopyrimidine(1H,3H)-2,4-diones with the Vilsmeier reagent affords, depending on the reaction conditions, either 6-dimethylaminomethylidene substituted 5H-pyrido[2,3-cflpyrimidine(1H,3H)-2,4-diones or the corresponding pyridopyrimidine( I H,3H)-2,4-di ones bearing a carboxaldehyde function in position 6 of the heterocycle. Some further transformations of the aldehyde function demonstrate the synthetic potential of the synthesized structures, introducing pharmacologically relevant basic substituents into the side chain of these pyrido[2,3-dlpyrimidine derivatives. (C) 2004 Elsevier Ltd. All rights reserved.