Tetrabutylammonium triphenyldifluorosilicate

Thus removal of water from classical rather inactive fluoride reagents such as tetrabutylammonium fluoride di- or trihydrate by silylation, e.g. in THF, is a prerequisite to the generation of such reactive benzyl, allyl, or trimethylsilyl anions. The complete or partial dehydration of tetrabutylammonium fluoride di- or trihydrate is especially simple in silylation-amination, silylation-cyanation, or analogous reactions in the presence of HMDS 2 or trimethylsilyl cyanide 18, which effect the simultaneous dehydration and activation of the employed hydrated fluoride reagent (cf, also, discussion of the dehydration of such fluoride salts in Section 13.1). For discussion and preparative applications of these and other anhydrous fluoride reagents, for example tetrabutylammonium triphenyldifluorosilicate or Zn(Bp4)2, see Section 12.4. Finally, the volatile trimethylsilyl fluoride 71 (b.p. 17 °C) will react with nucleophiles such as aqueous alkali to give trimethylsilanol 4, HMDSO 7, and alkali fluoride or with alkaline methanol to afford methoxytri-methylsilane 13 a and alkali fluoride. 

The THF-soluble salt tetrabutylammonium fluoride (TBF) is a common source of fluoride. An alternative reagent is tetrabutylammonium triphenyldifluorosilicate (TBAF).115 Unsymmetrical allylic anions generated in this way react with ketones at their less-substituted terminus. 

An intramolecular Michael reaction affording indolizidinones 166 was initiated by addition of tetrabutylammonium triphenyldifluorosilicate (TBAT) on allylsilanes 165 (Scheme 39) <2003TL6629>. 

Activation of 2-silyl-l,3-dithianes was effected by tetrabutylammonium triphenyldifluorosilicate <1996JOC6901> or CsF <1999TL2065>. Both, equatorial and even axial silyl groups were reacted with electrophiles with retention of the configuration at C-2 when CsF was used for activation (Scheme 64) <2002SL1447>. 

Pentacoordinated silicate TASF, one of the best activators of organosilicon compounds in the Pd-catalyzed cross-coupUng reaction as we have seen, is found to be involved in the coupling reaction with aryl hahdes in the absence of other organosilanes to give methylated arenes (Scheme 1A)S Recently, DeShong and co-workers also reported that tetrabutylammonium triphenyldifluorosilicate, another pentacoordinated silicate, is applicable for the phenylation of allyl benzoates and aryl haUdes in the presence of a palladium catalyst. 

Trimethylsilyl trifluoromethane 307 was another source of difluorocarbene when it was treated with catalytic amounts of tetrabutylammonium triphenyldifluorosilicate 308 (TBAT) or Nal (Scheme 1.151) [217],... 

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