An Effective Method for the Synthesis of 1,3‐Dihydro‐2H‐indazoles via N‐N Bond Formation.

The [4+1] cycloaddition reaction of bifunctional amino reagents has been achieved with in situ formed aza‐ortho‐quinone methides. Specifically, N‐(tosyloxy)carbamates were used as an N1 synthon and bifunctional amino reagents for this transformation, which provides a metal‐free, catalyst‐free, and oxidant‐free strategy to form nitrogen‐nitrogen bonds. [ABSTRACT FROM AUTHOR]