Studies on Pyrazolo[3, 4-d]pyrimidine Derivatives. XIV

The Reissert reaction of 1-phenyl-1H-pyrazolo[3, 4-d]pyrimidine (4) in anhydrous methylene chloride using benzoyl chloride, trimethylsilyl cyanide, and a catalytic amount of aluminium chloride gave the corresponding Reissert compound (3, 5-benzyol-4, 5-dihydro-1-phenyl-1H-pyrazolo[3, 4-d]pyrimidine-4-carbonitrile) in 95% yield.The alkaline hydrolysis of 3 in methanol resulted in the formation of 4, benzoic acid (7), and the 4, 4'-dimer (9) of 4. The acid hydrolysis in dimethyl sulfoxide and in methanol proceeded with ring fission to give 5-amino-α-benzamido-1-phenyl-1H-pyrazole-4-acetonitrile (13), the acetamide (14), and the acetate (15). Compound 3 reacted with sodium hydride in dimethylformamide to give 4, 9, 1-phenyl-1H-pyrazolo[3, 4-d]-pyrimidine-4-carbonitrile (20), α, 1-diphenyl-1H-pyrazolo[3, 4-d]pyrimidin-4-ylmethyl benzoate (21), and O-benzoylmandelonitrile (22).In the present paper, we compare the chemical properties of 3 with those of the isoquinoline Reissert compound (1, 2-benzoyl-1, 2-dihydro-1-isoquinolinecarbonitrile).