Abstract
The amino group at the 7-position on the 3H-1, 2, 3-triazolo[4, 5-d]pyrimidine ring was converted into halogen atoms by treatment with isopentyl nitrite in halomethanes, in satisfactory yields. The halogen-metal exchange reaction between 7-iodo-3-phenyl-3H-1, 2, 3-triazolo[4, 5-d]pyrimidine (2) and butyllithium in the presence of N, N, N', N'-tetramethylethylenediamine proceeded, giving the 7-lithio compound (9). The lithio compound (9) reacted smoothly with electrophiles to give the corresponding 7-substituted compounds (15-18). On the other hand, the reaction of 7-chloro-3-phenyl-3H-1, 2, 3-triazolo[4, 5-d]pyrimidine (1) with butyllithium gave the ring fission product, 5-amino-1-phenyl-1H-1, 2, 3-triazole-4-carbonitrile (14).
