Highly Chemoselective gem ‐Difluoropropargylation of Aliphatic Alcohols

Despite the potential of α‐fluoroethers in medicinal chemistry, their synthetic methods, especially etherification of aliphatic alcohols, have been limited. Herein, we developed two‐ and three‐step gem ‐difluoropropargylation of aliphatic alcohols including amino acid derivatives and naturally occurring bioactive molecules. Highly chemoselective etherification proceeded by using the gem ‐difluoropropargyl bromide dicobalt complex in the presence of silver triflate and triethylamine. Decomplexation of dicobalt complexes was achieved by using cerium ammonium nitrate or N , N , N′ ‐trimethylethylenediamine. The thus obtained gem ‐difluoropropargyl ethers were converted to various α‐difluoroethers which are expected to be useful for medicinal chemistry.