SYNTHESIS OF LKOXY-5H-PYRAZOLO[4,3-D]-1,2,3-TRIAZIN-4-(3H)-ONES

An efficient method for the preparation of lkoxy-5H-pyrazolo-[4,3-d]-1 ,2,3-triazin-4(3H)-ones 7a-n is described. Isopropyl 1,4-dinitropyrazo le-5-carboxylate (2) underwent aromatic nucleophilic ''cine'' substitu tion with concomitant ester hydrolysis to give 3(5)-alkoxy-4-nitropyra zole-5(3)-carboxylic acids 3a-c, when it was reacted with an alcoholic solution of potassium hydroxide at room temperature. The latter were converted into the final compounds 7a-n through a four step sequence, involving: i) carboxylic acid activation, ii) carboxamide formation, i ii) nitro group reduction, and iv) intramolecular diazotization.