Di-ferf-butylbiphenyl

When the halogen in the precursor is exceptionally mobile as an anion, even chloro compounds may give poor yields due to extensive self-destruction. For example, chloromethyl methyl ether can be expediently converted into methoxymethyllithium only if sodium/lithium alloy is used and a carefully elaborated protocol is meticulously followed . In the case of 7-chloronorbomadiene, the lithium/4,4 -di-ferf-butylbiphenyl radical anion has to be employed to further reduce the contact time between 7-norbornadienyllithium and its labile precursor. Many reductive metal insertions into... 

Since different reactivity is observed for both the stoichiometric and the catalytic version of the arene-promoted lithiation, different species should be involved in the electron-transfer process from the metal to the organic substrate. It has been well-established that in the case of the stoichiometric version an arene-radical anion [lithium naph-thalenide (LiCioHg) or lithium di-ferf-butylbiphenylide (LiDTBB) for using naphthalene or 4,4 -di-ferf-butylbiphenyl (DTBB) as arenes, respectively] is responsible for the reduction of the substrate, for instance for the transformation of an alkyl halide into an alkyllithium . For the catalytic process, using naphthalene as the arene, an arene-dianion 2 has been proposed which is formed by overreduction of the corresponding radical-anion 1 (Scheme 1). Actually, the dianionic species 2 has been prepared by a completely different approach, namely by double deprotonation of 1,4-dihydronaphthalene, and its X-ray structure determined as its complex with two molecules of N,N,N N tetramethylethylenediamine (TMEDA). ... 

A 50 mL, flame dried round-bottomed flask equipped with a magnetic stirrer bar and a 3-way tap with argon balloon was charged with lithium wire (70 mg, 10 mmol) and 4,4 -di-ferf-butylbiphenyl (2.25 g, 8.45 mmol). Distilled tetrahy-drofuran (25 mL) was then added at room temperature. After stirring for 10 min at room temperature, the mixture was cooled to 0 °C. The stirring was continued for 1 h at 0 °C to afford di-ferf-butylbiphenyllithium (LDBB) solution in THE (25 mL). 

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