Premium
Mild Copper‐Catalyzed Fluorination of Alkyl Triflates with Potassium Fluoride
Author(s) -
Dang Hester,
Mailig Melrose,
Lalic Gojko
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201402238
Subject(s) - catalysis , reagent , alkyl , chemistry , fluoride , copper , potassium , potassium fluoride , phase transfer catalyst , organic chemistry , inorganic chemistry
A chemoselective catalytic fluorination of alkyl triflates is described using potassium fluoride as a fluoride source. Excellent yields of the desired alkyl fluorides are obtained after one hour at 45 °C using 2 mol % of the copper catalyst. With 10 mol % of the catalyst, full conversion can be achieved in less than 10 minutes at 45 °C, and thus makes this procedure potentially suited for the preparation of 18 F‐labeled PET probes. As a result of the mild reaction conditions, only the substitution products are observed with no evidence of common side reactions, such as elimination. Reported is a preliminary study of the reaction scope, which demonstrates that the fluorination can be performed in the presence of a wide range of functional groups. Evidence suggests an unusual role of the [IPrCuOTf] catalyst as a phase‐transfer catalyst and points to [IPrCuF] as the active fluorinating reagent (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene).