Subject with organolithium compounds

Only the dry-looking fine powder should be used for reactions with organolithium compounds. If desired the powder may be subjected to a drying procedure involving heating for 1 h in a vacuum of 10 to 20 mmHg using a rotary evaporator (bath temperature between 50 and 60 °C). Under these conditions some depolymerization may occur. 

Although the subject of exchange reactions of organolithium compounds has recently been dealt with in detail (14, 15), a brief account is included here because of the many reactions between these compounds and the alkyl derivatives of Groups II and III. 

Several Lewis acid-base interactions between alkali metal cations and heteroatom-containing molecules are indispensable in the promotion of reactions involved in critically important and fundamental transformations—deprotonation with lithium amides at the a-hydrogens of carbonyl or imino compounds and the addition of organolithium compounds to such electrophilic substrates. Because it is impossible to cover the multitude of these and other closely related subjects, this chapter describes only briefly general aspects of current interest. 

Deprotonation of t-Bu-BisP (BH3)2 with 1.2 equivalents of s-BuLi/( )-sparteine formed a mixture of mono- and dilithiated t-Bu-BisP (BH3)2 whose - intermolecular oxidative coupling with Cu(II) afforded a mixture of tetraphosphine borane 86 and hexaphosphine borane 87. The use of ( )-sparteine may surprise the reader, as the reaction does not involve any enantioselective deprotonation. However, it was found that its presence was beneficial to activate the -BuLi, showing that ( )-sp is not only a chiral inductor, but also modifies the reactivity of the organolithium reagents. After separation by column chromatography, 86 and 87 were obtained in 26% and 14% isolated yields respectively. Tetraphosphine borane 86 was subjected to similar reactions, affording compounds 88 (29% yield) and 90 (8% yield), which contain 8... 

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