Other Organolithiums

Other Organolithium Compounds. Organoddithium compounds have utiHty in anionic polymerization of butadiene and styrene. The lithium chain ends can then be converted to useflil functional groups, eg, carboxyl, hydroxyl, etc (139). Lewis bases are requHed for solubdity in hydrocarbon solvents. 

Most isothiazoles are lithiated at the 5-position by the action of butyllithium or other organolithium compounds, provided that this position is vacant (65AHC(4)107, 72AHC(14)l, 77SST(4)339). 3-Methyl-4-nitroisothiazole, however, is inert (65AHC(4)107). 2,1-... 

Crystal structure determination has also been done with -butyllithium. A 4 1 n-BuLi TMEDA complex is a tetramer accommodating two TMEDA molecules, which, rather than chelating a lithium, link the tetrameric units. The 2 2 -BuLi TMEDA complex has a structure similar to that of [PhLi]2 [TMEDA]2. Both 1 1 -BuLi THF and 1 1 -BuLi DME complexes are tetrameric with ether molecules coordinated at each lithium (Fig. 7.2). These and many other organolithium structures have been compared in a review of this topic. ... 

IV. OTHER ORGANOLITHIUM COMPOUNDS A. Lithiation of Triphenyl((trimethylsilyl)imino)phosphorane, Ph3P=NSiMe3... 

See Lithium 3-(l,l,2,2-tetrafluoroethoxy)propynide See other organolithium reagents... 

By the extension of the above-mentioned stereoselective asymmetric addition of alkylithiums to other organolithium reagents such as lithium salts of methyl phenyl sulfide, 2-methylthiazoline, trialkylsilylacetylene, N-nitroso-dimethylamine, and acetonitrile, chiral oxiranes (95) U1), thiiranes (96) nl), acetylenic alcohols (98) 112), and amino alcohols (97) U1) were readily obtained. 

The high propensity of organolithium compounds to form mixed complexes with other organolithium species in solution has been utilized successfully in synthesis using chiral lithium amides. Either the chiral lithium amides have been added to organolithium reagents in an effort to achieve asymmetry in addition reactions, or various additives have been introduced to alter the reactivity or selectivity of the chiral lithium amides themselves, e.g. in deprotonation reactions. 

We complete this section with a study of the effect of TMEDA on the polymerization of methyl methacrylate lithium enolate in THF262. It was concluded that TMEDA hardly affects the kinetics of the polymerization and therefore the monomer-dimer equilibrium. From these figures, TMEDA does not seem to be a better ligand for lithium ester enolates than THF, in line with previous observations by Collum on other organolithium compounds263. 

Methyl lithium and butyl lithium are widely used for the synthesis of other organolithium compounds. For example, lithium cyclopentadienides are generally prepared by the reaction of the cyclopentadiene with butyl lithium. In contrast, the amido-alkali metal compounds are becoming increasingly important in the synthesis of organoalkali metal compounds with the heavier alkali metals. For example, l,2,4-tris(trimethylsilyl)-l,3-cyclopentadiene reacts with potassium bis(trimethylsilyl)amide to form potassium l,2,4-tris(trimethylsilyl)cyclopentadienide. ... 

Organolithium compounds can be converted to other organolithium compounds under high temperatures. For example, (hhthiomethane is produced from methyl lithium when heated between 223 and 226 °C. ... 

Carbon-Lithium Bonds 5.5.2 3. from Other Organolithiums... 

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