Lithium complexes arylation

The crystal structure of the lithium complex [Pr 2N(Ph)COLi(p-tmp)(p-Bu )ZnBu shows that the amide solvates the lithium ion through oxygen with zincation of the aryl occurring via interaction of the ortho aryl hydrogen Bu or tmp group." The crystal... 

The crystal structures of the lithium salts 8 with bulky aryl substituents exhibit monomeric structures and / -coordination of the dithiocarboxylate to the lithium atom (Fig. 2) [40]. Lithium complexes 9 and 10,bearing pyrazyl and pyridyl groups, respectively, also have monomeric structures, the former of which has / -coordination similar to that of 8. On the other hand, the lithium cation in 10 is chelated by one sulfur atom of the dithiocarboxylate and a nitrogen atom of the pyridyl group [4]. 

Keywords Lithiation Arene-chromium complexes Aryl-lithium Regioselectivity in arene lithiation... 

Soderquist and coworkers [4] have prepared 9-oxa derivatives of B-OMe-9-BBN and submitted its lithium complex to Suzuki cross-coupling to a variety of aryl and vinylbromides. The yields of both arylacetylenes and stereodefined enynes (Eq. 31.5) match or exceed those obtained in the 9-BBN [4a] process (Table 31.7) [4bj. 

The examples discussed thus far are classed as contacted ion pairs, as both distinct metals are contained within the same molecule. Since 2007, one example of a solvent-separated lithium tris(aryl) magnesiate (ie, the complex exists as distinct cationic and anionic moieties) has been reported. [Li (THF)4] [Mg(mesityl)3] , 5 (where mesityl is 2,4,6-trimethylphenyl) resembles many other trialkyl/aryl Hthium magnesiates and consists of a tetrahedraUy disposed tetra-THF-solvated lithium cation and a trigonal planar magnesium tris(aryl) anion (Fig. 5). ... 

Homoleptic lithium complexes [Li NNE 2]Cl (E = 0, S), containing Juc-coordinating NNE-donor hgands prepared from bis(3,5-dimethylpyrazol-l-yl)methanewith BuLi and alkyl- or aryl-containing isocyanates or isothiocyanates, have been used to synthesize a series of scandium and yttrium complexes. ... 

Many other organometaUic compounds also react with carbonyl groups. Lithium alkyls and aryls add to the ester carbonyl group to give either an alcohol or an olefin. Lithium dimethyl cuprate has been used to prepare ketones from esters (41). Tebbe s reagent, Cp2TiCH2AlCl(CH2)2, where Cp = clyclopentadienyl, and other metal carbene complexes can convert the C=0 of esters to C=CR2 (42,43). 

More recently, a very efficient asymmetric carbolithiation of N,N-dimethyl-aminofulvene 30, leading to a chiral cyclopentadienide anion, was reported by Hayashi et al. [6] for the synthesis of chiral metallocenes (Scheme 6). By adding an aryl lithium such as 31 complexed with a chiral ligand on fulvene 30, a cyclopentadienide ion 32 bearing a stereogenic center at the a position was generated. This anion was reacted with [RhCl(nbd)]2 to yield... 

Shibasaki showed that an aluminum-lithium-BINOL complex (ALB) also catalyzes the asymmetric addition of dialkyl phosphites to aldehydes, with ees ranging from 55 to 90% for aryl or unsaturated aldehydes (Scheme 5-37). 

A remarkable process was reported by Mori that forms aniline from dinitrogen (Equation (26)).106 Titanium nitrogen fixation complexes were generated from reactions of titanium tetrachloride or tetraisopropoxide, lithium metal, TMS chloride, and dinitrogen. These complexes generated a mixture of aryl and diarylamines in yields as high as 80% when treated with aryl halide and a palladium catalyst containing DPPF ... 

The 10-57-5-hydridosiliconate ion 62 is known in association with lithium,323 tetrabutylammonium,101 and bis(phosphoranyl)iminium93 cations. It is synthesized by hydride addition to the 8-.S7-4-silane 63, which is derived from hexafluoroacetone.101 Benzaldehyde and related aryl aldehydes are reduced by solutions of 62 in dichloromethane at room temperature101 or in tetrahydrofuran at 0°96 within two hours. The alkyl aldehyde, 1-nonanal, is also reduced by 62 in tetrahydrofuran at O0.96 Good to excellent yields of the respective alcohols are obtained following hydrolytic workup. The reactions are not accelerated by addition of excess lithium chloride,96 but neutral 63 catalyzes the reaction, apparently through complexation of its silicon center with the carbonyl oxygen prior to delivery of hydride from 62.101... 

Incorporation of additional donor functionality into the periphery of phosphinomethanide ligands also has dramatic consequences for the structures of their alkali metal complexes. The complex [Li C(SiMe2Ph)(PMe2)2 ]3 (49) crystallizes as solvent-free cyclic tri-mers (Fig. 18), in which each lithium is primarily coordinated by two P atoms from one ligand and the carbanion center of an adjacent ligand (138, 139). This is supplemented by an essentially -interaction with the ipso and an ortho-carbon of the phenyl ring associated with the carbanion bonded to lithium. Each Li is thus bound by two P atoms, two aryl carbons, and a central carbon of the phosphinomethanide ligands. 

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