A telechelic fluorinated diol from 1,6-diiodoperfluorohexane

The radical addition of 1-iodoperfluorohexane (1) to allyl alcohol (2-propen-1-ol) (2) was investigated in the presence of various initiating systems (photochemically or in the presence of redox catalysts or organic initiators), leading to C6F13CH2CHICH2OH (3) in various yields. A scale of efficiency of the involved radical system was proposed, triphenylphosphine and AIBN yielding the best conversions of 1. Interestingly, AIBN, when added three times in the course of the reaction was the most suitable for an almost quantitative consumption of 1. Then, 3 was reduced to C6F13C3H6OH (4) in high yields by tributylstannane. Such a two-step procedure was extrapolated to the preparation of the fluorinated telechelic diol from 1,6-diiodoperfluorohexane (5). First, the formations of both the 1-to-1 monoadduct (6) and 1-to-2 α,ω-diadduct (7) were noted and discussed: optimised conditions enabled production of 7 in 81% yield with a complete conversion of 5. Then, telechelic diol HOC3H6C6F12C3H6OH (8) was synthesised selectively in 88% yield, from the reduction of the iodine atoms of 7 by tributylstannane. 1H, 19F and 13C NMR spectroscopies allowed characterisation of all the intermediates and products without ambiguity.