Triazenolysis of alkenes as an aza version of ozonolysis

Abstract

Alkenes are broadly used in synthetic applications, thanks to their abundance and versatility. Ozonolysis is one of the most canonical transformations that converts alkenes into molecules bearing carbon–oxygen motifs via C=C bond cleavage. Despite its extensive use in both industrial and laboratory settings, the aza version—cleavage of alkenes to form carbon–nitrogen bonds—remains elusive. Here we report the conversion of alkenes into valuable amines via complete C=C bond disconnection. This process, which we have termed ‘triazenolysis’, is initiated by a (3 + 2) cycloaddition of triazadienium cation to an alkene. The triazolinium salt formed accepts hydride from borohydride anion and spontaneously decomposes to create new C–N motifs upon further reduction. The developed reaction is applicable to a broad range of cyclic alkenes to produce diamines, while various acyclic C=C bonds may be broken to generate two separate amine units. Computational analysis provides insights into the mechanism, including identification of the key step and elucidating the significance of Lewis acid catalysis.