Design, Synthesis, and Evaluation of a Novel Class of Enantioselective Electrophilic Fluorinating Agents:  N-Fluoro Ammonium Salts of cinchona Alkaloids (F-CA-BF4)

The first enantiopure N-fluoro quaternary ammonium salts of cinchona alkaloids as enantioselective fluorinating agents are reported. A one-step transfer-fluorination on the naturally occurring cinchona alkaloids gave the fluorinating agents F-CA-BF(4). 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.