Pyrrolo[2,1-d][1,2,3,5]tetrazines, a new class of azolotetrazines related to the antitumor drug temozolomide

A series of derivatives of the new ring system pyrrolo[2,1-d][1,2,3,5]tetra zine, potential antineoplastic agents, were obtained in good yield from the reaction of 2-diazopyrroles with isocyanates at room temperature and in th e dark. Atomic charges at C-4, a good parameter to predict the antineoplast ic activity for this type of compounds, were found to be very close to that of temozolomide (2), the antitumor drug currently used in therapy.