Lithium 2- methyl

The benzylidene derivative above is used, if both hydroxyl groups on C-2 and C-3 are needed in synthesis. This r/vzns-2,3-diol can be converted to the sterically more hindered a-cpoxide by tosylation of both hydroxy groups and subsequent treatment with base (N.R. Williams, 1970 J.G. Buchanan, 1976). An oxide anion is formed and displaces the sulfonyloxy group by a rearside attack. The oxirane may then be re-opened with nucleophiles, e.g. methyl lithium, and the less hindered carbon atom will react selectively. In the following sequence starting with an a-glucoside only the 2-methyl-2-deoxyaltrose is obtained (S. Hanessian, 1977). 

The product described here, 4-(4-chlorophenyl)butan-2-one, was previously prepared in the following ways a) by reduction of the corresponding benzalacetone, b) by catalyzed decarbonylation of 4-chlorophenylacetaldehyde by HFeiCO) in the presence of 2,4-pentanedione, - c) by reaction of 4-chlorobenzyl chloride with 2,4-pentanedione under basic catalysis (K2CO3 in EtOH), d) by reaction of 4-chlorobenzyl chloride with ethyl 3-oxobutanoate under basic catalysis (LiOH), - and e) by reaction of 3-(4-chlorophenyl )-propanoic acid with methyl lithium. - ... 

IQ. To determine the concentration of chloride ion, - a 5-mL aliquot of the methyl lithium solution is cautiously added to 25 ml of water and the resulting solution is acidified with concentrated sulfuric acid and then treated with 2-3 ml of ferric ammonium sulfate [Fe(NH4)( 04)2 12 H2O] indicator solution and 2-3 ml of benzyl alcohol. The resulting mixture is treated with 10.0 mL of standard aqueous 0.100 M silver nitrate solution and then titrated with standard aqueous 0.100 H potassium thiocyanate solution to a brownish-red endpoint. 

Although ethereal solutions of methyl lithium may be prepared by the reaction of lithium wire with either methyl iodide or methyl bromide in ether solution, the molar equivalent of lithium iodide or lithium bromide formed in these reactions remains in solution and forms, in part, a complex with the methyllithium. Certain of the ethereal solutions of methyl 1ithium currently marketed by several suppliers including Alfa Products, Morton/Thiokol, Inc., Aldrich Chemical Company, and Lithium Corporation of America, Inc., have been prepared from methyl bromide and contain a full molar equivalent of lithium bromide. In several applications such as the use of methyllithium to prepare lithium dimethyl cuprate or the use of methyllithium in 1,2-dimethyoxyethane to prepare lithium enolates from enol acetates or triraethyl silyl enol ethers, the presence of this lithium salt interferes with the titration and use of methyllithium. There is also evidence which indicates that the stereochemistry observed during addition of methyllithium to carbonyl compounds may be influenced significantly by the presence of a lithium salt in the reaction solution. For these reasons it is often desirable to have ethereal solutions... 

Lithium methylate (lithium methoxide) [865-34-9] M 38.0. Most probable impurity is LiOH due to hydrolysis by moisture. It is important to keep the sample dry. It can be dried by keeping in a vacuum at 60-80° under dry N2 using an oil pump for a few hours. Store under N2 in the cold. It should not have bands above 3000cm-> IR has VKBr 1078, 2790, 2840 and 2930cm-. [JOrgChem 21 156 7956.]... 

The rates of the reactions of several aromatic ketones with alkyllithium reagents have been examined. The reaction of 2,4-dimethyl-4 -(methylthio)benzophenone with methyl-lithium in ether exhibits the rate expression ... 

The first clearly authenticated preparation of an isoindole was reported by Wittig et in 1951. It was found that elimination from isoindolinium bromides and iodides with bases such as aryl- and alkyllithium afforded 2-substituted isoindoles in variable yields. For instance, 2,2-dimethylisoindolinium bromide (5) on treatment with one equivalent of phenyllithium in ether under nitrogen, evolved methane and gave 2-mcthylisoindole (6) in 74% yield. With methyl-lithium as base, a slightly lower yield was obtained. 

Dimesitylimidazolium chloride with nickelocene gives the carbene complex [(T) -Cp)NiCl(L)] (L= l,3-dimesitylimidazol-2-ylidene), in which the chloride ligand can be substituted by a methyl group by reacting the product with methyl-lithium (OOJOM(596)3). 

A more promising procedure for the formation of alkenes from tosylhydrazones is represented by the Shapiro reaction It differs from the Bamford-Stevens reaction by the use of an organolithium compound (e.g. methyl lithium) as a strongly basic reagent ... 

Having retraced the remarkably efficient sequences of reactions which led to syntheses of key intermediates 14 and 15, we are now in a position to address their union and the completion of the synthesis of the spiroketal subunit (Scheme 6b). Regiocontrolled deprotonation of hydrazone 14 with lithium diisopropylamide (LDA), prepared from diisopropylamine and halide-free methyl-lithium in ether, furnishes a metalloenamine which undergoes smooth acylation when treated with A-methoxy-A-methylcarboxa-mide 15 to give the desired vinylogous amide 13 in 90% yield. It is instructive to take note of the spatial relationship between the... 

To a solution of hexamethyldisilane (2.5 mmol) in HMPA (CAUTION— CANCER SUSPECT AGENT) (3 ml) at 0-5 °C was added methyl lithium (2.5 mmol, 1.5 m MeLi.LiBr complex in ether) dropwise. After being stirred for 3 min, the red solution was treated with Cul (2.5 mmol) in Me2S (1 ml), the resulting black reaction mixture was stirred for 3 min. and 2,3-dibromo-propene (1 mmol) was added rapidly via a syringe. The reaction mixture was allowed to warm to room temperature, and was stirred for 1.5 h. It was then poured into pentane (25 ml) and saturated ammonium chloride solution (25 ml, buffered to pH 8 by the addition of ammonium hydroxide), and the mixture was stirred vigorously for 1 h. The aqueous phase was re-extracted with pentane, and the combined organic extracts were dried. Removal of... 

Methoxytrimethylsilane, 123 Methyl acetoacetate, 92 Methyl bromoacetate, 107 Methyl 11-hydroxyundecanoate, 58 Methyl lithium, 27,28 Methyl 10-undecenoate, 58 2-Methyl-l, 3-dithiane, 81 (fl/ ,5 )-Methyl-3-phenyldiniethyl-silyl-3-phenylpropionic acid, 53-4 2-Methyl-3-Phenylprop-2-cnal, 111 2-Methyl 2-lrimethylsilyl-1,3-dithiane, 81 2-Methyl-l-(trimcthylsilyloxy)cyclo-hex-l-ene, 100,109 2-Melhyl-l-lrimethylsilyloxy)cyclo-hcx-6-enc, 100 2-Methyl-2-trimethylsilyloxy-pentan-3-one, 132 2-Methylacetophenone, 42-3 2-Methylbutyraldehyde, 85 2-Methylcyclohexanone, 99,100 2-Methylcyclohexanone, 131 4-Methyldec-4-ene, 67-8 Methylenation, 63 2-Methylpropen-l-ol, 131 Methyltriphenylphosphonium bromide, 27 Michael addition, 85 Monohydridosilanes, 128 Monohydroalumination, 29... 

To a solution of hexamethyldisilane (2.5 mmol) in HMPA (CAUTION— CANCER SUSPECT AGENT) (3 ml) at 0-5 °C was added methyl lithium (2.5 mmol, 1.5 m MeLi.LiBr complex in ether) dropwise. After being stirred for 3 min, the red solution was treated with Cul (2.5 mmol) in Me2S (1 ml), and the resulting black reaction mixture was stirred for 3 min. Ether (6 ml)... 

Terminal alkynes can be converted readily into alkynylsilanes by reaction of the corresponding alkyne anion or its metalloid equivalent with a suitable chlorosilane (/). The reverse reaction, that of liberation of the alkyne, is quite facile, being effected by several reagent combinations, including hydroxide ion, methanolysis, fluoride anion, silver(i) followed by cyanide anion, and methyl lithium-lithium bromide (2). 

Bis(diphenylphosphino)methyl-lithium, from methyl-lithium and bis-(diphenylphosphino)methane, gave the compound (1) with chlorodiphenyl-phosphine. ... 

The phosphoranes (14) readily undergo ligand exchange on treatment with organolithium reagents. Thus, (14 R = Ph) with butyl-lithium gave an almost quantitative yield of (14 R = Bu) whereas with the less basic methyl-lithium equilibrium was established between (14 R = Ph) and (14 R = Me). 

C. Alkyl and Aryl Derivatives.—Reactions of organometallic reagents, such as methyl-lithium, with fluorocyclophosphazenes are, in general,... 

The stepwise replacement of fluorine atoms in fluorocyclophosphazenes, (NPF2) n = 3—5), by methyl groups has been followed.and n.m.r. spectroscopy showed that methyl-lithium in diethyl ether generally effects a geminal replacement pattern. With N3P3F6, only mono- and di-methyl derivatives were obtained, but with N4P4F8 the dimethyl (52), trimethyl (53), and octamethyl derivatives were noted. The formation of... 

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