A recently recognized ambident reactivity of 2,3-diamino-isoquinolinium salts

Abstract

Reinvestigation of an old experimental finding -the formation of linearly fused tetrazoloisoquinolines from 2,3-diamino-isoquinolinium salts, by using 15 N-labeling and 15 N-NMR spectroscopy, revealed that the ring closure pathway -unlike a recently observed cyclization of the same diamino salt -does not proceed via a rearrangement route. By comparison of this reaction with the entirely different reactivities of other related 1,2-diamino-azinium salts, a general mechanism is suggested, revealing an ambident reactivity of these diamino compounds.