Enabling Access to 3‐<i>gem</i>‐Difluorovinyl Lactams via Zn‐Mediated Sequential Single Electron Reductive Hydrodehalogenation

Comprehensive Summary Herein, we describe a direct route for the synthesis of 3‐ gem ‐difluorovinyl lactams through Zn‐mediated reductive hydrodehalogenation. Importantly, by using inexpensive deuterium oxide (D 2 O), the high value‐added vicinal dideuterated gem ‐difluoroalkenes with excellent deuterium (D) incorporation were prepared. Mechanism studies indicated a successive single electron transfer process: the reaction initially undergoes hydrodechlorination to give the intermediate α‐ trifluoromethylidene lactams, which are then activated by the in‐situ generated zinc cations and reduced to the desired product via hydrodefluorination.