Synthesis of a novel ring-expanded purine analogue containing a 5:8-fused imidazo[4,5-e][1,2,4]triazocine ring system amidst opportunistic rearrangements and ring transformations

A novel 5:8-fused heterocycle containing the imidazo[4,5-e][1,2,4]triazocine ring system has been synthesized in ten steps commencing from 1-benzyl-5-methyl-4-nitroimidazole. The compound is a new member of the family of ring-expanded xanthine–xanthosine analogues reported from this laboratory. The synthesis led to the unraveling of a number of novel rearrangements and ring-transformations.