Synthesis of some 4-substituted 1-(4-hydroxybutyl)pyrazolo-[3,4-d]pyrimidine analogues of 9-(4-hydroxybutyl)guanine (HBG)

xThe chemical synthesis of some 4-substituted 1-(4-hydroxybutyl)pyrazolo [3,4-d]pyrimidines was described. Using solid-liquid phase transfer catalysis, the 4-alkylthio-1-(4-acetoxybutyl)pyrazolo[3,4-d]pyrimidines 3a-c were regioselectively prepared in good yields. The influence of the solvent, the catalyst and the base on yields of the reaction was investigated. The carboacyclonucleoside 4-methylthio-1-(4-hydroxybutyl)pyrazolo[3,4-d]pyrimidine a was served as the precursor for the preparation of the 4-methylamino 4d, 4-dimethylamino 4e, 4-benzylamino 4f, 4-amino 4g and 4-methoxy 4h analogues.