Reassigning pseudoiodinine

The brightly colored members of the pyrazolo[4,3-e][1,2,4]triazine family of natural products have the distinction of being one of only two naturally occurring ring systems in which nitrogen atoms outnumber carbon atoms. Seven compounds bearing this characteristic skeleton have been isolated and characterized, but no efforts have been made toward their total synthesis, until now. T. Ross Kelly, Eric L. Elliott, and colleagues at Boston College report the total synthesis of three of these compounds: nostocine A, fluviol A, and pseudoiodinine (J. Am. Chem. Soc. 2006, 128, 5646). In their efforts to synthesize pseudoiodinine, the researchers discovered that the original structural assignment for it-reported more than 30 years ago-is incorrect. The challenge in identifying the compound's correct structure is that there are six potential methylation spots within the molecule, one on the oxygen atom and five on the nitrogen atoms. With a little chemical detective work, the team was able to identify the atoms that were methylated and correctly reassign the structure of pseudoiodinine (shown).