Lithium aryls

Reactivity and yields are greatly enhanced by the presence of 0.5-1% Na in the Li. The reaction is also generally available for the preparation of metal alkyls of the heavier Group 1 metals. Lithium aryls are best prepared by metal-halogen exchange using LiBu" and an aryl iodide, and transmetalation is the most convenient route to vinyl, allyl and other unsaturated derivatives ... 

Lithium aryls react as typical carbanions in nonpolar solvents giving carboxylic acids with CO2... 

The first series of soluble oligo(/ ara-phenylene)s OPVs 24 were generated by Kern and Wirth [48] and shortly after by Heitz and Ulrich [49]. They introduced alkyl substituents (methyls) in each repeat unit and synthesized oligomers 24 up to the hexamer. Various synthetic methods, like the copper-catalyzed Ullmann coupling, the copper-catalyzed condensation of lithium aryls, and the twofold addition of organomelallic species to cyclohexane-1,4-dione, have been thereby investigated. 

The B-B bonded l,2-dimethoxydiborane(4) precursor67 was selected on the basis that it could be obtained readily from (MeO)2B-B(OMe)268 by reaction with the lithium aryl. In contrast to diborane(4) tetrahalides,... 

The direct oxidation of lithium aryl tellurolates into the ditellurides without previous aqueous work-up is exemplified by the preparation of di(2,4,6-tri-t-butylphenyl) ditel-luride. ... 

Thiinium cations, e.g. (140), react with lithium aryls to give complex mixtures containing some 1,2,4,6-tetrasubstituted thiabenzenes (141) (see CHEC 2.02.5.4.5). 

Diazines also react more readily than pyridine. Thus, pyrimidine and phenylmagnesium bromide give adduct (276), which can be oxidized to 4-phenylpyrimidine. Aryl- and heteroaryl-lithium reagents at low temperature (79AG1, 80RTC234) add across the 3,4-double bond of pyrimidines to give dihydropyrimidines. 2,5-Dimethylpyrazine and lithium aryls afford the 3-aryl derivatives. 

There is a large series of lithium alkyls and lithium aryls which are useful m organic chemistry in much the same way as the magnesium Grignard reagents. Unlike Na, K, Rb, or Cs, but like Mg, lithium reacts directly with nitrogen to form a nitride ... 

The known reactivity of phenanthridine towards lithium aryls extends to the hindered o-tolyllithium, where the stability of the 6-o-tolyl-5,6-dihydrophenanthridine allows its isolation.314 (6-Phenyl-phenanthridine forms 6,6-diphenyl-5,6-dihydrophenanthridine under similar conditions.62,314)p-Biphenylyllithium reacts smoothly to give the dihydro adduct oxidation in situ with boiling nitrobenzene gives the 6-biphenylylphenanthridine in good yield.327... 

Ham and coworkers85 have developed a one-pot synthetic method for the formation of aryl-alkyl sulfides, 94, from various alkyl halides and lithium aryl thiolates 93, which are prepared in situ from 92 formed by lithium—halogen exchange of 91, employing n-butyllithium (Scheme 31). The method avoids the use of unstable arylthiols and a catalyst is not required. Several aryl bromides were successfully employed in the reaction, and the corresponding sulfides were obtained in 71 to 96% yields. 

Lithium aryls have been less studied but several structures are known, e.g., [Li(2,4,6-Pr QH2)]442 and Li(2,4,6-Ph2QH2)(OEt2)2,43 the latter being monomeric with planar 3-coordination of Li. 

The alkyl can be collected by sublimation or distillation in a vacuum. On the other hand, the aryls are made by reaction of a lithium aryl in a hydrocarbon with BeCl2 in diethyl ether ... 

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