Sulfonium, tris difluorotrimethylsiliconate

Scheme 2.12 Sources of naked fluorides and some examples of their syntheses (TASF = tris(dimethylamino)sulfonium difluorotrimethylsiliconate) [33—38].

A number of oi ganoaluminum reagents, especially Me2AlCl, have been found to be effective catalysts for reactions of enol silyl ethers with aldehydes.It is possible that in these reactions, aluminum enol-ates may be involved as the intermediates. Similarly, bismuth trichloride has been reported to be an efficient catalyst.Since BiCh is considered to be a weak Lewis acid, the involvement of a bismuth enolate is perhaps implicated. Enolate intermediates are definitely generated when tetraalkylammonium fluorides or tris(dialkylamino)sulfonium (TAS) difluorotrimethylsiliconates (104) are used as reagents to promote the reactions of enol silyl ethers. Their chemistry will therefore not be discussed in this chapter. 

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