1.2.4- Triazin-5-ones, 3-azido-, cyclization

Azido-2H-l,2,4-triazin-3-ones (56a) also cyclize to give the tetrazolo[5,l-d]-[l,2,4]triazin-3-ones (56b) (71RRC135, 71RRC311). Nitrosation of 3-amino-6-hydrazino-l,2,4-triazin-5-one (57) affords a compound which exhibits an intense absorption at 2140cm-1, showing that the 6-azido tautomer (58a) was isolated. When this compound was stirred for a few minutes in a polar solvent it quantitatively formed the tetrazole tautomer (58b) (79JHC555). 

Azido-l,2,4-triazincs (44) spontaneously cyclizc to give the tctrazolo[l,5-Z)][l,2,4]triazincs (45), if cyclization to N-2 is possible no cyclization to N-4 was observed. 5-Azido-2//-l,2,4-triazin-3-ones... 

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