Dehydration-Activation of Inorganic and Organic Salts

The dehydration and activation of commercial tetrabutylammonium fluoride di-or trihydrate to obtain anhydrous BU4NF [10, 11] is compHcated because the highly active anhydrous BU4NF decomposes already at T 14—17°C to give tri-butylamine, tributylamine hydrofluoride, 1-butylfluoride, and 1-butene [12]. Thus 

3SnCl2-2H20 4Tcs l4/MeCN 3 SnCI -e 6 Me3SiOSiMe3 7-t 4 NH4CII 

As described in Section 7.4, hexamethyldisilane 857 reduces, analogously, pyridine, quinoline and isoquinoline N-oxides to the free bases [17] and converts aromatic nitro groups to azo compounds [12]. Likewise, as already discussed allyltti-methylsilane 82 and benzylttimethylsilane 83 will gradually dehydrate and activate BU4NF-2-3H20 in situ to catalyze the addition of 82 and 83 to pyridine, quinoline, and isoquinoline N-oxides [13] (cf Section 7.2). 

Conversion of Inorganic Oxides into the Corresponding Halides and Triflates 

All these silicon reagents which activate metal surfaces are also Lewis acids, which can also contribute as such to the acceleration of any of the subsequently discussed reactions, because of their inherent Lewis acid properties. 

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