Conformation-induced regioselective and divergent opening of epoxides by fluoride: facile access to hydroxylated fluoro-piperidines.

Utilizing molecular conformation as a controlling factor, epoxide-containing 2-aryl-piperidines can be ring-opened with the reagent combination of tetrabutylammonium fluoride (TBAF) and potassium bifluoride (KHF2) in a regioselective and divergent fashion. Four different types of hydroxylated fluoro-piperidines, valuable building blocks in drug development, were readily synthesized using this method. The basic nature of the reagent combination allowed a one-pot deprotection/ring opening process, which increased the efficacy of this transformation.