Triazolo[4,5-d]pyrimidines. XII. Reaction of 6-Benzoyl-6,7-dihydro-3-phenyl-3H-1,2,3-triazolo-[4,5-d]pyrimidines (Triazolopyrimidine Reissert Compounds) with Acid, Base, and Electrophile

In the treatment of 6-benzoyl-6,7-dihydro-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidine-7-carbonitrile (1,triazolo-pyrimidine Reissert compound) and 6-benzoyl-6,7-dihydro-5-methyl-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidine-7-carbonitrile (2,5-methyltriazolopyrimidine Reissert compound) with an acid, the ring fission of the pyrimidine ring proceeded to give the triazole derivatives (3-7). Alkaline hydrolysis of 2 and 1 gave 5-metyl-3-phenyl- (10) and 3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidines (9), respectively. The anions, generated from 1 and 2 with sodium hydride (NaH), underwent aromatization to give the 3H-1,2,3-triazolo[4,5-d]pyrimidine-7-carbonitriles (12 and 14). Compounds 1 and 2 reacted with arylaldehydes in the presence of NaH to give corresponding 3H-1,2,3-triazolo[4,5-d]pyrimidin-7-ylmethyl benzoates (15 and 17).