Synthesis of Heteroaryl Triazenes via Rh(III)‐catalyzed Annulation Reactions with Alkynyl Triazenes

A synthetic route towards polycyclic heteroaryl triazenes has been developed. Alkynyl triazenes were coupled to phenyl‐substituted indoles, imidazoles and sydnones via rhodium‐catalyzed double C−H or C−H/N−H activation reactions. The oxidative annulations gave triazenes connected to imidazo[1,2‐a]quinoline, indolo[2,1‐a]isoquinoline and sydnone‐quinoline scaffolds in moderate to excellent yields. The triazene‐bearing fused sydnone‐quinolines were used for subsequent orthogonal transformations. The sydnone moiety allowed for post‐functionalization via 1,3‐dipolar cycloadditions in excellent yields, and the triazene group can be substituted by a range of functional groups.