Synthesis of Enantioenriched Alkylfluorides by the Fluorination of Boronate Complexes

The enantiospecific conversion of
chiral secondary boronic esters
into alkylfluorides is reported. Boronate complexes derived from boronic
esters and PhLi were used as nucleophiles, with Selectfluor II as
the electrophilic fluorinating agent, to afford alkylfluorides in
short reaction times. The addition of styrene as a radical trap was
found to enhance enantiospecificity. A broad range of alkyl boronic
esters were converted into alkylfluorides with almost complete enantiospecificity
by this method.