A fast and efficient 'on-solvent' cascade assembling of salicylaldehydes and dimethylbarbituric acid into 5-(1,3-dimethyl-2,4-dioxo-1,3,4,5-tetrahydro-2H-chromeno[2,3-d]pyrimidin-5-yl)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-triones

A fast (15 min) and efficient cascade reaction of salicylaldehydes and 1,3-dimethylbarbituric acid in the presence of p-TsOH as a catalyst furnishes substituted 5-(1,3-dimethyl-2,4-dioxo-1,3,4,5-tetrahydro-2H-chromeno[2,3-d]pyrimidin-5-yl)-1,3-dimethylpyrimidine-2,4,6(1H, 3H, 5H)-triones 1a-h, containing both chromeno[2,3-d]pyrimidine and hexahydropyrimidine-2,4,6-trione pharmacologically active fragments, in 95-99% yields. This new procedure is characterized by the use of inexpensive reagents and a simple workup.