Studies on Pyrazolo [3, 4-d] pyrimidine Derivatives. IX. On 4-(p-Tolylsulfonyl)-1-phenyl-1H-pyrazolo [3, 4-d] pyrimidine

4-(p-Tolylsulfonyl)-1-phenyl-1H-pyrazolo [3, 4-d] pyrimidine (I) is hydrolyzed by dil. hydrochloric acid into 1, 5-dihydro-1-phenyl-4H-pyrazolo [3, 4-d] pyrimidin-4-one (III), and the p-tolylsulfonyl group undergoes nucleophilic substitution with hydroxide, methoxide, hydrazine, butylamine, aniline, and cyanide. Application of active methylene compound, nitrile, or ketone in the presence of sodium amide results in substitution with a carbanion. When ketone is used as the carbanion source, reaction product differs with reaction conditions. For example, the use of acetone results in the formation of 1-(P-4-yl)-2-propanone (X7) or 1, 1-bis (P-4-yl)-2-pronone (X7), where P-4-yl denotes 1-phenyl-1H-pyrazolo [3, 4-d] pyrimidin-4-yl group. When 2-butanone (X8) is used, the product is either 3-(P-4-yl)-2-butanone (X8-2) or 1, 1-bis (P-4-yl)-2-butanone (X8'-1). In these cases, III is formed at the same time and its process of formation was discussed. In some cases, 5-(P-4-yl)-1, 5-dihydro-1-phenyl-4H-pyrazolo [3, 4-d] pyrimidin-4-one (XI) is formed as a by-product.