H-(CF2)(10)-CH2OH --> (5steps) I-(CF2)(8)-CH2OAc
The applicability of telomeric alcohols, H(CF2CF2)(n)CH2OH, for the synthes
is of omega -functionalized F-alkylating reagents, I(CF2CF2)(n-1)CH2OAc (6,
n = 5), is demonstrated. The key steps of this optimized method are the "a
ctivation" of the HCF2- terminus in a lithiation process yielding olefin 2
[(Z+E)-BuCF=CF(CF2CF2)(4)CH2OH, 86%] and a successive ozonation reaction in
trifluoroethanol media affording ester 3b [CF3CH2O2C(CF2CF2)(4)CH2OH, 93%]
. Highly stereospecific ozone cleavage of the (E)-2 isomer was observed in
methanol due to the competitive oxidation of the solvent.