SYNTHESIS OF ACYCLO C-NUCLEOSIDES - 6,7-DIPHENYL-1,2,4-TRIAZOLO[4,3-B][1,2,4]TRIAZINES

Condensation of 3-hydrazino-5,6-diphenyl-1,2,4-triazine (1) with aldop entoses 2a-d or aldohexoses 2e-g gave the corresponding aldehydo sugar (5,6-diphenyl-1,2,4-triazin-3-yl)hydrazones 3a-g. A one-step oxidativ e cyclization with subsequent acetylation of these hydrazones by treat ment with bromine in acetic acid in the presence of anhydrous sodium a cetate followed by acetylation with acetic anhydride gave the correspo nding 6,7-diphenyl-1,2,4-triazolo[4,3-b][1,2,4]triazines 5a-g. De-O-ac etylation of the latter compounds with methanolic ammonia gave ol-1-yl )-6,7-diphenyl-1,2,4-triazolo[4,3-b][1,2,4] triazines 6a-g.