Aryllithium reagents

Formation of aryl Grignard reagents (Section 14 4) Aryl halides react with magnesium to form the corresponding arylmagnesium halide Aryl iodides are the most reac tive aryl fluorides the least A similar reaction occurs with lithium to give aryllithium reagents (Section 14 3)... 

The sesquiterpenoid hydrocarbons (5)-a-curcumene (59) and (5)-xanthorrhizol (60) were prepared by asymmetric conjugate addition of the appropriate aryllithium reagent to unsaturated oxazoline 56 to afford alcohols 57 (66% yield, 96% ee) and 58 (57% yield, 96% ee) upon hydrolysis and reduction. The chiral alcohols were subsequently converted to the desired natural products. ... 

The reaction gives good yields with primary, secondary, and tertiary alcohols, and with alkyl and aryllithium reagents.Allylic alcohols also couple with certain... 

Most other organometallic compounds also react with oxygen. Aryllithium reagents have been converted to phenols by treatment with oxygen. Trialkylboranes and alkyldichloroboranes (RBCI2) can be conveniently converted to hydroperoxides by... 

The alkylation of heterocyclic nitrogen compounds with alkyllithium reagents is called Ziegler alkylation. Aryllithium reagents give arylation. The reaction occurs... 

The reactions of aryllithium reagents are accelerated by inclusion of potassium... 

Arylcopper intermediates can be generated from organolithium compounds, as in the preparation of cuprates.95 These compounds react with a second aryl halide to provide unsymmetrical biaryls in a reaction that is essentially a variant of the cuprate alkylation process discussed on p. 680. An alternative procedure involves generation of a mixed diarylcyanocuprate by sequential addition of two different aryllithium reagents to CuCN, which then undergo decomposition to biaryls on exposure to oxygen.96 The second addition must be carried out at very low temperature to prevent equilibration with the symmetrical diarylcyanocuprates. 

Alkoxy groups can be displaced from boron by alkyl- or aryllithium reagents. The reaction of diisopropoxy boranes with an organolithium reagent, for example, provides good yields of unsymmetrically disubstituted isopropoxyboranes.3... 

To immobilize such anions as borate, organoboron polymers were reacted with aryllithium reagents.31,32 The reaction of alkylborane polymers with n-BuLi was examined first however, the ionic conductivity of the resulting material was very low. Moreover, complicated peaks were observed in the H-NMR spectrum. Conversely, selective lithium borate formation was observed in the nB-NMR spectrum when PhLi was employed (scheme 6). An ionic conductivity of 9.45 X 10 7Scm 1 was observed at 50°C. The observed ionic conductivity was relatively low because of the decreased number of carrier ions compared with dissolved salt systems. However, the lithium transference number of this polymer was markedly high (0.82 at 30°C). 

Reactions of organoboron polymer electrolytes with aryllithium reagents suffered low conversion due to relatively low reactivity of the mesitylborane unit. Moreover, incorporation of aryl substituent in side chains resulted in higher glass-polymer electrolyte-transition temperatures. 

The most straightforward synthesis of compounds (L)AuAr uses the metathesis of (L)AuX precursors with aryllithium reagents, as, for example, executed for the preparation of (Ph3P)AuPh. The crystal structure of this benchmark complex has been determined. The linear coordination geometry is as expected. No aurophilic contacts are discernible in the crystal packing. Short Au- -Au contacts are observed, however, in the dinuclear compound (dppm)(AuPh)2 with an intramolecular intermetallic distance of 3.154(1) A. This complex shows a UV-VIS absorption at 290-300 nm and is luminescent in fluid solution at room temperature.1... 

An aryllithium reagent, prepared from 1-bromo-2,6-diethylbenzene and butyllithium, reacts with SnCl2 in THF at 0°C to produce hexakis(2,6-diethylphenyl)tristannacyclopro-pane, 47, in 50-55% yield883. If the reaction above is performed at 0°C in Et20, the 1-butyl-2,2,3,3,4,5,5,6,6-nonakis(2,6-diethylphenyl)hexastannabicyclo[2,2,0]hexane, 48, can be isolated in 1.5% yield. This compound turns out to be the first example of a polycyclic polystannane88b. 

Xu and co-workers performed similar transformations on cr,/3-unsaturated tert-butyl esters 5 with aryllithium reagents. The use of functionalized substrates and aryllithiums is the key feature of this study (Scheme 3).6... 

Alkyllanthanum triflates, RLa(OTf)2. Alkyl- or aryllithium reagents are known to cleave tertiary amides to ketones, but yields are low because of a further reaction with the ketone to form a tertiary alcohol. The amides can be cleaved to ketones in high yield by reaction with alkyl- or aryllanthanum triflates, generated in situ by reaction of RLi or ArLi with La(OTf), (equation I). 

Eight Al(Por)R complexes (For = OEP,TPP R = Me, "Bu, CeHs, C6F4H) were prepared from the reaction of Al(Por)Cl with an alkyl or aryllithium reagent. Mass spectra of the compounds showed low intensities for the molecular ion peaks, consistent with facile cleavage of the Al—C bond. The chloride complexes Al(Por)Cl show normal porphyrin UV-visible spectra, whereas the organometallic complexes Al(Por)R show a split Soret band typical of hyperporphyrin spectra. 

The preparation of aryllithium reagents can also be performed by using t-butyllithium in a halogen-metal exchange, and aqueous potassium ferricyanide as an oxidant. 

A special case of functionalized aryllithium reagents appears when the corresponding aryl group bears a ketal moiety at the benzylic position due to the lability of the benzyUc carbon-oxygen bonds. However, working under Barbier-type conditions and using naphthalene (10%) as the electron carrier catalyst, the reaction of chlorinated materials 242 afforded, after hydrolysis with water, the corresponding polyfunctionalized products 243 (Scheme 81). ... 

Chiral /3,/3-diaryIpropionic acid moieties are often found in compounds showing biological activities, such as antiarrhythmics vasodilators antidepressives " , antihistamines and controllers of cerebral insufficiency ". In the course of synthetic studies of chiral -diaryIpropionic acid derivatives, Merck researchers developed stereoselective conjugate addition of aryllithium reagents to the a,/ -unsaturated fert-butyl esters 18 bearing a chiral imidazolidine or oxazolidine auxiliary at the ortho position of an aryl group. The addition furnished chiral -diaryIpropionic acid derivatives 19 with... 

Several further publications report on the (—)-sparteine-mediated addition of alkyl-or aryllithium onto imines or the C=N bond of isoquinolines . Usually, the achieved enantiomeric excesses are low and, sometimes, other chiral ligands serve better. As reported by Muller and coworkers, the nucleophilic substitution of arenecarbaldehyde dialkyl acetals by o-substituted aryllithium reagents is an alternative . 

The use of a catalytic amount of the homochiral ligand is here allowed by the poor reactivity of aryllithium reagents toward oxiranes, the reaction being supposed to occur through the more reactive organolithium/Schiff base complex 109, as depicted in Scheme 49. 

C-aryl glycals in 75-92% yields. It consisted in the addition of aryllithium reagents to variously protected 2-deoxy-aldono-l,5-lactones, followed by treatment with a mixture of pyridine (Py), 4-(Dimethylamino)pyridine (DMAP), and trifluoroacetic anhydride (TFAA). 

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