TASF reagent
From Wikipedia, the free encyclopedia
| TASF reagent | |
|---|---|
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| IUPAC name | Tris(dimethylamino)sulfonium difluorotrimethylsilicate |
| Identifiers | |
| CAS number | [59218-87-0] |
| SMILES | C\[N](C)=S(N(C)C)/N(C)C.C[Si](C)(C)(F)F |
| Properties | |
| Molecular formula | C9H272N3SSi |
| Molar mass | 275.48 g mol-1 |
| Appearance | Colorless solid |
| Melting point |
98-101 °C |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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The TASF reagent or tris(dimethylamino)sulfonium difluorotrimethylsilicate is a reagent in organic chemistry with structural formula [((CH3)2N)3S]+[F2Si(CH3)3]-. It is an anhydrous source of fluoride and is used to cleave silyl ether protective groups. Many other fluoride reagents are known, but few are truly anhydrous, because of the extraordinary basicity of "naked" F-. In TASF, the fluoride is masked as an adduct with the weak Lewis acid trimethylsilylfluoride (FSi(CH3)3). The sulfonium cation ((CH3)2N)3S+ is unusually non-electrophilic due to the electron-donating properties of the three (CH3)2N substituents.
This compound is prepared from sulfur tetrafluoride:
- 3 (CH3)2NSi(CH3)3 + SF4 → 2 (CH3)3SiF + [((CH3)2N)3S]+[F2Si(CH3)3]-
The colorless salt precipitates from the reaction solvent, diethyl ether.
[edit] References
- W. J. Middleton, Tris(dimethylamino)sulfonium difluorotrimethylsilicate, Organic Syntheses, Coll. Vol. 7, p.528 (1990); Vol. 64, p.221 (1986) Online article
