Dianions, generation, lithium naphthalenide

Dianion Generation. Lithium naphthalenide efficiently de-protonates alkynyloxy " and carboxylate anions (eq 5). In addition, the previously mentioned phenomenon of reductive metalation has been exploited to access dianions fromhalohydrins, -halo carboxylic acids, and -halo carboxamides, and even trianions from -dihalo alcohols. A major pathway for the polyanionic species is -elimination (eq 6) when such processes can be avoided, the polyanions react according to Hauser s rule (eq... 

The treatment of tetrakis di-fbutylmethylsilyl) disilene (3) with 2 equiv of lithium naphthalenide (LiNp) in THF-ds generates the dilithium-substituted dianion which can be characterized spectroscopically Si NMR (8) = -199.4 ppm). Upon replacing THF solvent with benzene the cleavage of the Si—Si bond leads to the formation of disilenyllithium (Scheme 6.2.1.1) (4). 

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