Triazole[4,5-d]pyrimidines. IX. Reactions of 5-Chloro- and 5-(Methylsulfonyl)-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidines with C-Nuclephiles

The nuclephilic substitution of 5-(methylsulfonyl)-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidine (2) with potassium cyanide proceeded smoothly to give 3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidine-5-carbonitrile (6), but the same reaction did not take place in the case of 5-chloro-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidine (1).Compounds 1 and 2 reacted with ethyl cyanoacetate in the presence of sodium hydride in tetrahydrofuran, giving ethyl α-cyano-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidine-5-acetate (7). When acetote was used as a ketone, it added across the C^7,N^6-double bond, giving 7-acetonyl-5-chloro-6,7-dihydro- (8a) and 7-acetonyl-6,7-dihydro-5-(methylsulfonyl)-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidines (8b), respectively, although the yields were low.The reaction of 1 with Grignard reagents resulted in the formation of addition products such as 7-alkylated 5-chloro-6,7-dihydro-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidines (9a-e). The substitution of the methylsulfonyl group of 2 with Grignard reagents proceeded to give the corresponding 5-alkylated 3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidines (11a-e).