Lithium 2- -5-methylphenyl

PLiC,H 2, Lithium, (2-(methylphenyl-phosphino)ethyll-, 27 178 PLiSi2CjH,g20C4Hg, Phosphide, bis(tri-methylsilyl)-, lithium, —2tetrahydro-furan, 27 243,248... 

OXIRANES (Dimethylamino)phenyl-oxosulfonium methylide. Dimethyl-sulfonium methylide. (Dimethyl sulfoxide, derived reagent (b)). Methylene bromide-Lithium. Methylphenyl-N-p-tohienesulfonylsulfoximine. 

ENOL ETHERS Trimethylchlorosilane. EPISULFIDES Sulfur monochloride. EPOXIDES Dimethylformamide dimethyl acetal. Dimethyloxosulfonium methylide. Iodine. Methylene bromide-Lithium. Methylphenyl-N-p-toluene-sulfonylsulfoximine. a -EPOXY SULFONES Hydrogen peroxide. 

Methylphenyl)benzothiazole (80IC762) and 2-benzylbenzothiazole (95ICA(239)125) can be cyclopalladated. In the latter case, cylopalladation occurs upon reaction with palladium(II) acetate and gives the product 80. With lithium chloride, sodium bromide, or sodium iodide, a series of three products of substitution of the acetate group 81 (X = C1, Br, I) results. Pyridine, 2- and 3-methylpyridine, 2,6- and 3,5-dimethylpyridine cause the transformation of the chelate complexes 81 (X = C1, Br, I) and formation of the mononuclear products 82 (R = z= R" = = R = H, X = Cl, Br, I ... 

The reduction of optically active methylphenyl-n-propylphosphine sulphide with lithium aluminium hydride proceeds with 100% retention, whereas the reaction of phosphine oxides with lithium aluminium hydride leads to racemization. ... 

Benzylic deprotonation occurs under normal lithiation conditions when both ortho-positions are occupied. Interestingly, Thomas and co-workers were able to deprotonate a benzylic proton in the presence of an ortho proton (Scheme 8.137). Thus, metalation of 2-(2-methylphenyl)oxazoline 424 produced a benzylic lithium species that reacted with a Cbz-protected leucinal 425 to give a modest yield of the iminolactone diastereomers 426 and 427 together with the expected alcohols 428 and 429. The mixture of 426—429 was efficiently hydrolyzed to give the lactones 430 and 431. 

Alkylation with 1-bromopropane was shown to give the S-configurated 1-methylphenyl-butyl diisopropylcarbamate preferentially. This result is remarkable as alkylation, in this case, occurred by a metalloretentive mode, in contrast to that generally observed on alkylation of benzylic lithium compounds. 

Di-/m-butyl-4-methylphenyl cyclopropanecarboxylatc (8) can be quantitatively lithiated by treatment with 1 equivalent of le/7-butyllithium at — 78 °C in tetrahydrofuran 64 to give an amine-free, slightly yellow solution of the lithium species 9, which is then attacked by an electrophile to furnish the alkylated product 10 in good yield. Diastereomers were obtained when R1 = CH3 or C6H5. 

Substituted 3,6-dialkoxy-2,5-dihydropyrazines are regioselectively metalated by strong alkyl-lithium bases, such as butyllithium, (l-methylpropyl)lithium, fcrf-butyllithium, or lithium diiso-propylamide, at the less substituted carbon atom (C5). Metalation proceeds at low temperatures (in general, below — 70 C) in THF as solvent. Electrophiles suitable for alkylation of the lithiated derivatives include alkyl iodides, bromides and chlorides, as well as alkyl methanesulfonates, 4-methylbenzenesulfonates and trifluoromethanesulfonates. The electrophile adds trans to the substituent at C2 in a highly stereoselective fashion, with typical diastereomeric excesses of greater than 90% (syn addition has been reported in only one case where a-methylphenyl alanine was used as chiral auxiliary and an alkyl trifluoromethanesulfonate as electrophile18). 

Dimethylamino)methyl]-5-methylphenyl]lithium is a white crystalline solid and is pyrophoric in air. Furthermore, it is soluble in hydrocarbons and ethers. Molecular weight determinations in benzene have established a tetrameric structure.12 In THF, like [2-[(dimethylamino)-methyl]phenyl]lithium, this tetramer breaks down to a dimeric species. 

Esters of 2-(2-methylphenyl)hydrazinecarboxylic acids can be metallated with lithium diisopropylamide (LDA) and the resulting polyanions condensed with aromatic esters and lead to acid-catalysed cyclization to 1-isoquinolones... 

The neutral solution is poured into collector 15, and from there into tank 16. The tank is also filled with a calculated amount of a 10% solution of lithium hydroxide. Vapour heating is started and toluene is distilled, first under atmospheric pressure, then in vacuum. The distillation is finished when the distillate no longer enters receptacle 18, which is achieved approximately at 180 °C and a residual pressure of 52-80 GPa. From the receptacle, toluene is sent into batch box 3 for repeated use. The products of the hydrolytic condensation of methylphenyldichlorosilane, methylphenyl-cyclosiloxanes, are sent from tank 16 into collector 19 and then into tank 20 to decompose. 

Lithium aluminum hydride reduced 9-hydroxy-9-(4-methylphenyl)-telluraxanthene to 9-(4-methy lpheny l)-telluraxanthene1. 

MethylphenyI)-teUuraxanthene1 0.5 g (13 mmol) of lithium aluminum hydride and 3.0 g (23 mmol) of aluminum trichloride are suspended in 50 ml of absolute diethyl ether. To the stirred suspension at 20 are added 1.60g (4 mmol) of 9-hydroxy-9-(4-methylphenyl)-telluraxanthene and the mixture is heated under reflux for 1 h. After cooling, it is diluted by slow addition of 50 ml of diethyl ether, the resultant solution is poured into 100 ml of 20% aqueous sulfuric acid, the mixture is filtered, and the filtrate separated into two layers. The aqueous layer is washed with two 50 ml portions of diethyl ether. The organic phases are combined, dried with anhydrous sodium sulfate, filtered, and the filtrate is evaporated yield 1.23 g (80%) m.p. 1G3°. 

Methylphenyl)-telIuraxanthylium perchlorate was reduced by lithium aluminum hydride to 9-(4-methylphenyl)-telluraxanthene3. 

Dimethyl-lO-elhylphenotellurazine1 A 500 ml round bottom flask equipped with a reflux condenser, a dropping funnel, and a stirrer is flushed with argon and then charged with a solution of 15 g (39 mmol) of bis[2-bromo-4-methylphenyl]ethylamine in 150 ml of dry diethyl ether. The flask is cooled in an ice/waler bath, 54 ml (78 mmol) of a 1.54 molar solution of butyl lithium in diethyl ether are added, and the solution is stirred for 45 min. 16 g (42 mmol) of tellurium diiodide are added, the mixture is stirred and heated under reflux for 1 h, cooled, and poured into 250 m/of ice/water. The hydrolyzed mixture is filtered, the filter cake is washed with two 50 ml portions of diethyl ether, and the combined ether solutions arc dried with anhydrous calcium chloride. After filtration, the filtrate is evaporated, and the residue is recrystallized from octane yield 8.1 g (55%). 

Hellwinkel (22) ingeniously removed the problem of para bromination by starting with tris(4-methylphenyl) amine, which exclusively bromi-nates in the required three ortho positions. Unfortunately, although ortho dimetallation occurs when diphenylamine is treated with alkyl-lithium reagents, triphenylamine is lithiated in the meta positions (23) presumably due to the steric effects the triphenyls of other Group V elements cleave when reacted with LiR derivatives. 

The molecular structure of the first compound comprises a polymeric chain, consisting of alternating [(C6H4CH2NMe2 2)2Cu] anionic and [Ii2(CN)(THF)4] cationic units. In the cationic unit, two lithium atoms are end-on bridged by the cyanide group, and two additional THF molecules are coordinated to each lithium atom. The fourth coordination site is occupied by the nitrc en atom of the adjacent (dimethylamino)methylphenyl group of the [(C6H4CH2NMe2-2)2Cu] anionic unit. 

Seebach has also studied the utility of esters in organometallic acylation. In this case, preformed ester enolates of 2,6-di(t-butyl)-4-methylphenyl esters (BHT esters) were slowly warmed above -20 C to form the corresponding ketene. If this was done in the presence of an ad tional equivalent of alkyl-lithium the ketene was trapped to give a ketone enolate in high yield. The same reaction failed to give any product when simple esters such as methyl, ethyl or Nbutyl were uscd. Scheme 17 is illustrative of the method. 

Bis[(p,2-chloro)bis(tetrahydrofuran)-lithium] bis[pentakis(4-methylphenyl)-bismuthate]... 

Iododibenzobismole 331 lododiphenylbismuthine 199, 204 Lithium hexaphenylbismuthate 304 Mesitylene-bismuth chloride cr-complex 207 4-Methoxyphenylbis(4-methylphenyl)bismuthine 29 Methyl bis(4-methyl-l-naphthyl)bismuthinate 319 Methylbis(4-methylphenyl)bismuthine 34 Methylbismuth bis(O-alkyldithiocarbonate) 123 Methylbismuth dithiolates 122 Methylbis(2,4,6-triisopropylphenyl)bismuthine 24 (4-Methylphenyl)triphenylbismuthonium tetrafluoroborate 288 1-Methyltetrahydrobismole 335 Oxybis(triphenylbismuth) bis(benzenesulfonate) 281 Oxybis(triphenylbismuth) dicyanate 280 Oxybis(triphenylbismuth) diperchlorate 279... 

For the 2,6-di-fetT-4-methylphenyl esters this bulky group completely prevents hydrolysis however, it can be reducdvely removed with lithium aluminum hydride to provide cyclo-propanemethanols in very high optical purity95. Thus, 16 is the catalyst of choice for many cyclopropanation reactions. 

Similarly, a qualitative relation between the chemical behavior and the distortion from ideal C2v symmetry was suggested for a series of lithium ester enolates (Scheme 6.13) [108]. Enolate 1, furthest along the reaction coordinate to ketene, had to be handled at temperatures below -50°C and decomposed rapidly at temperatures higher than -30°C. The two other enolates, 2 and 3, were found to survive in crystalline form at 0°C and at room temperature, respectively. The decomposition occurs most likely through a ketene-like intermediate, whose transient existence was demonstrated by cleaving the lithium enolate of 2,6-di-/ert-butyl-4-methylphenyl-2-methylpropanoate at room temperature in the presence of excess -BuLi. 

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