Deoxygenative gem-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine

Background: 1,1-Difluoroalkenes cannot only be used as valuable precursors for organic synthesis, but also act as bioisosteres for enzyme inhibitors. Among various methods for their preparation, the carbonyl olefination with difluoromethylene phosphonium ylide represents one of the most straightforward methods. Results: The combination of (chlorodifluoromethyl)trimethylsilane (TMSCF(2)Cl) and triphenylphosphine (PPh(3)) can be used for the synthesis of gem-difluoroolefins from carbonyl compounds. Comparative experiments demonstrate that TMSCF(2)Cl is superior to (bromodifluoromethyl)trimethylsilane (TMSCF(2)Br) and (trifluoromethyl)trimethylsilane (TMSCF(3)) in this reaction. Conclusion: Similar to many other Wittig-type gem-difluoroolefination reactions in the presence of PPh(3), the reaction of TMSCF(2)Cl with aldehydes and activated ketones is effective.