Uncatalyzed four-component synthesis of pyrazolopyranopyrimidine derivatives and their antituberculosis activities

Fused pyrazolopyranopyrimidines containing both biologically active pyranopyrazole and pyranopyrimidine compounds were synthesized using a one-pot, four-component reaction of ethyl aceto acetate, hydrazine hydrate, benzaldehydes, and thiobarbituric acid without catalyst in ethanol. All target compounds obtained in very good to excellent yields over short reaction times by adapting a simple workup procedure. All the synthesized compounds exhibited good to excellent antituberculosis activities. The results shown that 4-(1H-imidazol-2-yl)-3-methyl-7-thioxo-4,6,7,8-tetrahydropyrazolo4’,3′:5,6]pyrano2,3-d] pyrimidin-5(1H)-one (5a) is a good antitubercular agent, as good as the standard streptomycin drug, based on minimum inhibitory concentration (MIC).