Synthesis of acyclo C-Nucleosides of H1-antihistaminic 4-substituted [1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones

Synthesis of New 3,7,9-Trisubstituted Pyrazolo[4,3-e][1,2,4]Triazolo[4,3-c] Pyrimidines Acyclo C-Nucleosides via Oxidative Cyclisation

Condensation of 4-hydrazino-1,3-diphenylpyrazolo[3,4-d]-pyrimidine with the aldohexoses, namely, D-glucose, D-galactose, D-mannose and the aldopentoses, D-arabinose, D-xylose and D-ribose, by heating in an aqueous ethanol in the presence of a catalytic amount of HCl, gave the respective aldehydo-sugar hydrazones. Oxidative cyclisation of such hydrazones by stirring with iron(III) chloride in ethanol at room temperature afforded the expected acyclo C-nucleosides 3-substituted-7,9-diphenylpyrazolo[4,3-e][1,2,4]triazolo[4,3-c]-pyrimidines. The structures of the cyclised sugar hydrazones were confirmed by their elemental analyses and spectral data.