Transition-Metal-Free Allylic Defluorination Cross-Electrophile Coupling Employing Rongalite

The conversion of CF3-alkenes to gem-difluoroalkenes using reductive cross-coupling strategy has received much attention in recent years, however, the use of green and readily available reducing salt to mediate these reactions remains to be explored. In this work a concise construction of gem-difluoroalkenes, which requires neither a catalyst nor a metal reducing agent, was established. Rongalite, a safe and inexpensive industrial product, was employed as both a radical initiator and reductant. This procedure was compatible with both linear and cyclic diaryliodonium salts, enabling a wide variety of substrates (>70 examples). The utility of this approach was demonstrated through gram-scale synthesis and efficient late-stage functionalizations of anti-inflammatory drugs.