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

Abstract 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. magnified image