A Pd-Catalyzed [4 + 2] Annulation Approach to Fluorinated N-Heterocycles.

3-Fluoro- and trifluoromethylthio-piperidines represent important building blocks for discovery chemistry. We report a simple and efficient method to access analogs of these compounds that are armed with rich functionality allowing them to be chemoselectively derivatized with high diastereocontrol.