Naphthalene reductive silylation

The observations101 that l,2-bis(TMS)-l,2-dihydro-naphthalene (141)101,102 reacts with further chlorotrimethylsilane (142) to afford tris- and tetrakis(TMS)-tetrahyd-ronaphthalenes (143,144a, b) and rearrangements101 were an early example of the so-called reductive silylation (Scheme 19). 

The same mechanism is an explanation for the following results where l-(tri-methylsiloxy)naphthalene (145) and l,5-bis(trimethylsiloxy)naphthalene (146) can be converted via reductive silylation into 1-TMS-naphthalene (147) and 1,5-bis(TMS)-naphthalene (148) respectively103,104 (Scheme 20). 

A very common route to naphthyltrialkylsilanes is reductive silylation of e.g. l-(240) or 2-trimethylsiloxynaphthalene (242), or of l,5-bis(trimethylsiloxy)naphthalene (244) which can all be converted into the corresponding TMS-naphthalene compounds 241, 243 and 245, respectively, by means of Me3SiCl/Na (equation 115)144,145. A reactive intermediate... 

Table 9. Reduction potentials of silyl-substituted naphthalenes [68]...

Lithium naphthalenide (prepared from lithium and 1.33 equivalents of naphthalene) also reductively cleaves benzyl ethers [Scheme 4.143], Some functionalities survive the reaction conditions like carbon-carbon double bonds, benzene rings, THP ethers, silyl ethers and methoxymethyl ethers. A ketone group can be present but its prior conversion to an enolate is necessary. A similar transformation, but with a catalytic amount of naphthalene, has been reported. Although allyl ethers are also cleaved by the procedure, the selective deprotec-... 

Unlike carbanions and silyl anions, boryl anions (BR2"), in the form of boryllithiums, have been unknown until recently. In 2006, Japanese researchers reported the synthesis of a boryllithium via the reduction of a cyclic (diamino)bromoborane with lithium/naphthalene in THF, that is, Li+Np , where Np is the anion radical of naphthalene (Segawa, Y. Yamashita, M. Nozaki, K. Science 2006, 314, 113-115) ... 

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