Aryllithiums, pure

This type of halogen-lithium exchange can also be effected with many halo-genated aliphatic and aromatic hydrocarbons for example, pure aryllithiums can be obtained from aryl iodides and butyllithium in benzene.66... 

The well established alkylation of phosphorylated benzyl carbanions has been complemented by the arylation of purely alkyl species. Thus, diethyl (chloromethyl)phosphonate reacts with aryllithium reagents to give the diethyl esters of benzylic phosphonic acids The alternative procedure has been adopted in a synthetic route to isoprenyl (phos-phinylmethyl)phosphonates. Here, a lithiated dialkyl alkylphosphonate is acylated using an ester of the phosphonochloridic acid, R P(0)(0H)C1, where R is an isoprenoid residue. The acylation process has also been carried to with (R0)2P(0)C1 or (Me2N)2P(0)Cl ... 

In a chiral approach to ferrocenyldiamines, various aryllithiums, in the presence of sparteine, and in toluene, were added to 6-dimethylaminofulvene, leading to chiral lithium cyclopentadienides. The latter can be transformed into fer-rocenes, via an Fe(II) salt. When the arylhthium is ortho-substituted by a methyl, and in the presence of a chiral binaphthyl alcoholate, instead of sparteine, the ratio of chiral to meso-ferrocene is 88/12 (in 94% yield) and the chiral one is almost pure (ee>99%) (Scheme 31) [52]. 

The condensation of (31) with trichlorosilane, followed by reduction of the intermediate with LAH and distillation at 140-160°C (0.01 mm Hg), afforded an almost pure sample of the dibenzo[6/]silepin (32) in 53% yield <86JOM(304)93>. The compounds (33 R = R = Me or R = TMS, R = Me, H) were also prepared from the corresponding aryllithium salts <9IOM3l89>. Detailed structural investigations were performed on these compounds in the solid state and in solution. Replacement of chlorine in (33 R = H, R = Cl) by fluorine was effected with copper(II) fluoride the fluoride was subsequently converted into (34) by treatment with KF/18-crown-6 <89103190,910M1758). 

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