Organolithiums making

This method suffers from the presence of the aromatic species in the product mixture, leading to purification difficulties, but the high yield of many different organolithiums makes the method attractive. For example, conversion of 4-bromo-octa-... 

Until recently, the main route to simple a-lithiosilanes was addition of organolithiums to vinylsilanes, with all the obvious limitations involved. However, reductive lithiation (8) of phenylthioacetals using lithium 1-dimethylaminonaphthalenide (LDMAN) makes the following general Iprocess of considerable value ... 

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. 

This reagent was obtained either from Aldrich Chemical Company, Inc., or Lithium Corporation of America, Bessemer City, NC. A technical data sheet is available from the suppliers. Solutions of ca. 2 M were titrimetrically analyzed for active alkyllithium by the tosylhydrazone method. It is advisable to make certain that the organolithium reagent to be used was prepared in pentane solution. This evaluation can be easily accomplished by the gas chromatographic analysis of the organic layer obtained from the hydrolysis, under a nitrogen atmosphere, of the tert-butyllithium solution to be used. Isobutane and pentane should comprise essentially all of the... 

Anionic polymerization has also been used to make telechelic polymers (Greek telos, end, and chele, claw), i.e., polymers with reactive terminal groups.We coined the term, telechelic in 1957 and it has been accepted ever since in technical as well as patent literature. Liquid carboxy- and hydroxy telechelic polybutadienes initiated with difunctional organolithium initiators are commercially produced since 1962. Some of the physical properties,production details and uses as in solid rockets... 

The living character of organolithium polymerizations makes such processes ideally suited for the preparation of pure as well as tapered-block copolymers. Diene-olefin pure-block copolymers have become important commodities because of their unique structure-property relationships. When such copolymers have an ABA or (AB) X [A = polyolefin, e.g., polystyrene or poly(a-methylstyrene) B = polydiene, e.g., polybutadiene or polyisoprene and X = coupling-agent residue] arrangement of the blocks, the copolymers have found use as thermoplastic elastomers (i.e., elastomers that can be processed as thermoplastics). 

Oxyfunctional organolithium reagents which are very useful synthons are easy to make by stannylation of aldehydes followed by a destannylation with an organolithium (equations 209 and 210)104. 

Sparteine is the most important chiral ligand for lithium, and will be discussed in greater detail in chapters 5 and 6. However, irrespective of its chirality, it is included in this list as it often leads to important enhancements of reactivity even when enantioselectivity is not required.15 (-)-Sparteine can also make a very suitable replacement for toxic HMPA.16 Another class of ligand yet to be exploited are terminal alkenes, which appear to be able to affect the outcome and selectivity of certain organolithium reactions,17 perhaps by forming a Li—1 complex.18... 

The ease with which brominated heterocycles may be prepared regioselectively makes the use of these compounds as starting materials for the synthesis of regioselectively lithiated heterocycles extremely attractive. Organolithium derivatives of all the simple heterocycles at all possible positions of substitution have been made by this method.80 The scheme below illustrates some classical methods for forming 2-lithio-,81 3-lithio-,81 and 4-lithiopyridines,82 along with 4-lithioquinoline.83 rc-BuLi works well in these reactions, and indeed may be better than r-BuLi in reactions with electron deficient heterocycles, with which it tends to undergo addition reactions. 

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