Pd-Catalyzed Heck-Type Cascade Reactions with <i>N</i>‑Tosyl Hydrazones: An Efficient Way to Alkenes via in Situ Generated Alkylpalladium

A palladium-catalyzed Heck-type cascade reaction of aryl halides and N-tosyl hydrazones is reported. The neopentylpalladium species, generated from an intramolecular Heck-type insertion reaction of aryl halides, could efficiently react with carbenes to form highly functionalized alkenes. The synthesis of spiro compounds was also explored via a multiple Heck-type insertion reaction with N-tosyl hydrazone.