Diastereoselective Synthesis of 2,3,4,5,6-Pentafluoroheptanes

A stereocontrolled synthesis of alkanes containing five contiguous fluorine atoms is presented. The compounds were prepared by sequential fluorination of diastereoisomeric alcohol-diepoxides. The chemistry involved epoxide ring-opening with HF·NEt3 and deshydroxyfluorination reactions of free alcohols with Deoxo-Fluor. The fluorination reactions were all highly stereospecific, with all five fluorines being incorporated in three sequential steps. Three different diastereoisomers of the 2,3,4,5,6-pentafluoroheptyl motif were prepared as heptane-1,7-diol derivatives, a structural format amenable for incorporation of the vicinal pentafluoro scaffold into larger molecular architectures.