A facile and efficient DMAP-catalyzed [4+2] annulation of allenoates with arylazosulfones is developed for the synthesis of tetrahydropyridazine derivatives under mild and metal-free conditions, and this tandem cycloaddition exhibits high functional group tolerance and easy manipulation. In addition, the tetrahydropyridazine derivatives can be transformed into pyridazin-3-one derivatives in the presence of DDQ.

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.