Naked silyl anion

A silicon-silicon bond of hexamethyldisilane (159) is cleaved by BU4NF in hexa-methylphosphoric triamide (HMPA) to produce a naked silyl anion and fluorotri-methylsilane [58]. The resulting silyl anion undergoes aldehyde addition to afford, after acidic workup, 1-trimethylsilyl-l-alcohols like 160 (Scheme 5.41). The silyl anion can react with 1,3-dienes to give l,4-bis(trimethylsilyl)-2-butene 161 with high ( )-selectivity. 

Super anions. Unlike quaternary ammonium fluorides, 1 can be obtained anhydrous, li reacts with enol silyl ethers to form an unsolvated tris(diethylamino)-sulfonium (TAS) enolate in which there is negligible interaction hetween the ions.3 The naked enolate undergoes C-alkylation at —78 to — 30°. ... 

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