Organic Sulfinyl and Sulfonyl Fluorides

Compared to a trifluoromethyl group, it has been shown that the SF5 group has a similar but often enhanced effect on the lipophilic-ity of compounds and on essentially any physical or chemical property that derives from its strong polar influence. It also has the advantage of greater hydrolytic stability than does a trifluoromethyl group. 

To a significant extent, the interest in compounds bearing an SF5 group is a direct result of the increased availability of SF5-containing building blocks, as well as by the appearance in the literature of new and convenient methods for incorporating SF5 into aliphatic and aromatic compounds. 

FIGURE 7.5. Typical 19F NMR signals for an SF5 group, in this case for (pentafluoro-sulfanylmethylene)cyclohexane 

In the proton spectrum, the vinylic hydrogen appears as a pentet at 8 6.14 with a three-bond F-H coupling constant of 9 Hz, which means that only the equatorial fluorines couple to the hydrogen. There appear to be no examples of the axial fluorine of an SF5 group exhibiting 

In the above 13 C NMR spectrum, the vinylic carbon bearing the SF5 group appears as a pentet (2/FC = 17.0 Hz) at 8 132.34, with the other vinylic carbon also exhibiting coupling (3/FC = 5.0 Hz) and appearing at 

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