Linchpin Synthons:  Metalation of Aryl Bromides Bearing a Potassium Trifluoroborate Moiety

Aryl bromides bearing a potassium trifluoroborate moiety were subjected to lithium−halogen exchange at low temperature using a variety of alkyllithium reagents. A number of different electrophiles were evaluated in their reactions with the aryllithiums produced therein. Under carefully optimized conditions, potassium bromophenyl trifluoroborates afforded good to excellent yields of the corresponding alcohols (64−94% isolated yield) when aldehydes or ketones were used as the electophilic partner. Esters were unfortunately found to be unreactive.