Design, Synthesis, and Evaluation of a Novel Class of Enantioselective Electrophilic Fluorinating Agents:  <i>N</i>-Fluoro Ammonium Salts of <i>cinchona</i> Alkaloids (F-CA-BF<sub>4</sub>)

The first enantiopure <i>N</i>-fluoro quaternary ammonium salts of <i>cinchona</i> alkaloids as enantioselective fluorinating agents are reported. A one-step transfer−fluorination on the naturally occurring <i>cinchona</i> alkaloids gave the fluorinating agents F-CA-BF<sub>4</sub>. This new generation of fluorinating agents exhibited asymmetric induction up to 61% on fluorination of enolates and silyl enol ethers of 2-methyl-1-tetralone.