A Direct Route to Tetrahydropyridazine Derivatives via DMAP‐Catalyzed [4+2] Annulation of Allenoates with Arylazosulfones

Comprehensive Summary Herein, a DMAP‐catalyzed [4+2] annulation of α‐substituted allenoates with arylazosulfones is reported, which affords facile access to tetrahydropyridazine derivative in synthetically useful yields. This reaction features mild conditions and good functional group tolerance. Moreover, the resultant products can be readily transformed into pyridazin‐3‐one derivatives in the presence of DDQ.