Synthesis of Some Imidazopyrazolopyrimidines, Pyrazolopyrimidopyrimidines and Pyrazolopyrimidothiazines

Chloroacylation of 3-amino-2-phenylpyrazole-4-carboxamide (2) using chloroacetyl-(propionyl) chloride affording 6-chloromethyl(ethyl)-1-phenylpyrazolo [3,4-d]pyrimidin-4[5H]-one (3) or (6).Chlorine atom in com pound (3) or ( 6) underwent nucleophilic substitution reaction with primary or secondary amines to give 6-alkyl(aryl)aminomethyl(ethyl)-1-phenylpyrazolo [3,4-d]pyrimidin-4[5H]-one (4a-g,7a-f).When arylaminomethyl(ethyl)pyrazolopyrimidine was treated with formaline (30%) solution in ethanol, underwent Mannich reaction to afford imidazopyrazolopyrimidines (5a-e) and pyrazolopyrimidopyrimidines (8a-e).Chloromethyl pyrimidine derivative 3 was converted into the corresponding mercaptomethylpyrazolopyrimidene 9, Which cyclized using bromomalononitrile or phenacyl bromide into pyrazolopyrimidothiazine 11,12.