Organolithium compounds called

Chromium carbene complexes like 13, which are called Fischer carbene complexes, can conveniently be prepared from chromium hexacarbonyl 11 and an organolithium compound 12, followed by an O-alkylation step ... 

There are multiple systems for naming organolithium compounds. In one, CeHsLi is named phenyl lithium and w-C4H9Li is w-butyl lithium. In another, these species are named Uthiobenzene and 1-lithiobutane, respectively, when the lithium atom is regarded as a substituent on the hydrocarbon parent. A third nomenclature approach assumes these species are ionic salts, e.g. the above two compounds are called lithium phenylide and lithium butylide. We will bypass any questions of aggregation by referring to these compounds by their monomeric names (e.g. phenyl lithium and not dimeric phenyl lithium, phenyl lithium dimer nor diphenyl dilithium), and where monomeric species are actually meant, we will make this explicit. 

Meanwhile, development of coordination catalyst was proceeding full scale. The polyisoprene prepared using this coordination catalyst (TiClj, AIR ) proved to be more suitable in physical properties than the one made by lithium metal or organolithium compounds in hydrocarbon media. The Ziegler polyisoprene, as it was called, has greater stereoregularity and stress-induced crystallization properties than polyisoprene made by the alkyl lithium catalyst. How-... 

The base catalyzed decomposition of arylsulfonylhydrazones of aldehydes and ketones to provide alkenes is called the Bamford-Stevens reaction. When an organolithium compound is used as the base, the reaction is termed the Shapiro reaction. The most synthetically useful protocol involves treatment of the substrate with at least two equivalents of an organolithium compound (usually MeLi or BuLi) in ether, hexane, or tetramethylenediamine. The in s/ft formed alkenyllithium is then protonated to give the alkene. The above procedure provides good yields of alkenes without side reactions and where there is a choice, the less highly substituted alkene is predominantly formed. Under these reaction conditions tosylhydrazones of a,(3-unsaturated ketones give rise to conjugated dienes. It is also possible to trap the alkenyllithium with electrophiles other than a proton. 

Other bases may be employed, e.g. lithium hydride, sodium hydride, sodium amide or sodium in ethylene glycol with sodium in ethylene glycol, the reaction is called the Bamford-Stevens reaction. Aldehyde tosylhydrazones (200) do not form dianions with organolithiums, but the reagent adds to the carbon-nitrogen double bond to give the dilithium derivative (201) which decomposes to the organolithium compound (202). 

When Grignard reagents, organolithium compounds, or complex metal hydrides add to amides, the elimination step is slow at —78 °C, especially when the amine component is — N(Me)OMe (so-called Weinreb amides). When the tetrahedral intermediate is sufficiently long lived, quenching of the reaction mixture with water at —78 °C gives the ketone or aldehyde rather than the alcohol. 

Two equivalents of organolithium compounds also react with one equivalent of a Cu(I) salt, usually Cul, to give useful reagents called Gilman reagents. 

Alkyltriphenylphosphonium halides are only weakly acidic, and a strong base must be used for deprotonation. Possibilities include organolithium reagents, the anion of dimethyl sulfoxide, and amide ion or substituted amide anions, such as LDA or NaHMDS. The ylides are not normally isolated, so the reaction is carried out either with the carbonyl compound present or with it added immediately after ylide formation. Ylides with nonpolar substituents, e.g., R = H, alkyl, aryl, are quite reactive toward both ketones and aldehydes. Ylides having an a-EWG substituent, such as alkoxycarbonyl or acyl, are less reactive and are called stabilized ylides. 

Organonitrogen-lithium compounds, and particularly lithium amides (R2NLi), are widely used both in organic and in organometallic syntheses. For the former, these strong bases are employed as proton abstractors (5-8), to generate new organolithiums. These can then be derivatized with so-called electrophiles, e.g., alkyl and acyl halides (E+ = R+ and R—C+=0) and trimethylsilylchloride (E+ = MeaSi+) [Eq. (1)]. 

Diorganomercury(II) compounds react with Li metal to give organolithiums and Hg, a reaction best referred to as a metal displacement but often called a transmetallation ... 

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