“On-water” defluorophosphorylation of trifluoromethylated enones with phosphine oxides

The distinctive fluorine effects on “on-water” chemistry have remained less explored. In this work, an “on-water” reaction of β-trifluoromethylated enones with phosphine oxides was developed for the preparation of highly functionalized gem-difluorodienes with excellent Z-selectivity. The reaction occurred through a well-designed tandem phospha-Brook rearrangement and defluorination sequence under transition-metal-free conditions in water solution, which efficiently overcame some competitive side reactions, such as hydrodefluorination, 1,4-nucleophilic addition, and phosphorylation. The success was attributed to favorable H-bonding interactions at the water-organic phase boundary which could activate the substrates and enhance the reaction selectivity.