Lithium butyl, reaction

C. The mixture was cooled to -70°C and the allene (0.22 mol) was added in 5-10 min while maintaining the temperature between -60 and -70°C. After stirring for an additional 30 min at -60°C the solution was ready for further conversions. In the raetallation with ethyllithium the salts initially present had disappeared almost completely after this period. During the lithiation with commercial butyl-lithium the reaction mixture was continuously homogeneous. The solution of the lithiated allenes should be kept below -60°C and used within a few hours. 

Studies of alkyl halide-lithium alkyl reactions have been almost wholly concerned with proton polarization. The one exception to date is an investigation of polarization in the reaction of n-butyl lithium with p-fluorobenzyl chloride giving p,p -difluorobibenzyl (A/E multi-plet) and l-fluoro-4-pentylbenzene (E/A) (Rakshys, 1970). Surprisingly H-polarization is not observed. 

In the case of symmetrical divinyl tellurides, the displacement of both vinyl groups is achieved by employing 2 equiv of n-butyllithium. Aryl vinyl tellurides give a mixture of products, since both Ar-Te and vinyl-Te bonds are transmetallated on reaction with n-BuLi, leading to vinyl- and aryllithiums. The butyl vinyl tellurides give only the desired vinyl-lithiums. The reactions are stereospecific with retention of the C=C bond geometry. °... 

Geurink and Klumpp measured the protodelithiation enthalpies of 3-lithiopropyl methyl ether, 3-lithiobutyl methyl ether, 5-lithiopentyl methyl ether and 7-5yn-methoxy-2-exo-lithionorbornane in the same study that was discussed in an earlier section for the non-oxygenated compounds n-propyl lithium, n-butyl lithium, 5ec-butyl lithium and 2-norbornyl lithium. The reaction enthalpies for the oxygen-containing lithium species with 5ec-butyl alcohol in benzene were —190 2, —199 4, —190 3 and —199 2 kJmoU, respectively, where all of the lithiated ethers purportedly exist as tetrameric species. 

This procedure was extended to a method for asymmetric synthesis of optically active epoxides starting from optically active sulfoxides. As the oxiranyUithium 131 reacts with the acidic hydrogen of the n-butyl aryl sulfoxide, the introduction of electrophiles to the reaction mixture was problematic. Therefore, the reaction was performed by addition of 1 equivalent of f-C4H9Li at — 100°C to 130 and the sulfoxide-lithium exchange reaction was found to be extremely rapid (within a few seconds at this temperature). Moreover, as f-butyl aryl sulfoxide 138 has now no more acidic hydrogen, the addition of several electrophiles leads to functionalized epoxides 139 (equation 48). ... 

The heterocyclic 2,5-dilithio-3,4-di-(f-butyl)thiophene (78) could be generated by Nakayama and coworkers, starting from the corresponding 2,5-dibromo compound 77. The bromide-lithium exchange reaction was effected using two equivalents of... 

Interestingly, if the tribromo compound is treated with five equivalents of n-BuLi, then tetralithiation occurs, as was shown by the isolation of an a-butyl-2,4,5-trimethylthio derivative after reaction with excess dimethyl-disulfide [87JCS(P1)1453]. The a-butyl group in the product is derived from reaction of the a-benzyl carbanion with the n-butyl bromide produced by the initial bromine-lithium exchange reaction (Scheme 59). However,... 

Markl, Lieb and Martin were also able to add arynes 112 to 2.4,6-tiiphenyl-X -phosphorins the yields are better with 2.4.6-tri-tert-butyl-X -phosphorin. Here again 1,4 addition takes place with the formation of the 1-phosphabarfelenesiii. The arynes were generated either from 2-fluorophenylmagnesium bromide or penta-chlorophenyl-lithium. The reaction of the more nucleophilic 2.4.6-tri-tert-butyl-X -phosphorin with benzene-diazonium carboxylate also leads to 1,4 addition. The structure of the benzo-phosphabarrelenes 113a-d is supported by analytical and spectroscopic data (Table 16). 

Preparation of the Living" Polystyrene. 18 g of the living polymer was prepared by standard anionic polymerization using n-butyl lithium. The reaction was carried out by the dropwise addition of 20 ml of styrene to 5 ml of the initiator solution in 150 ml of neat THF at -78°C. The styrene drip was adjusted to take approximately 30 min for completion and then the reaction was allowed to stir for two hours before the grafting reaction with mesylated lignin was carried out. The number average molecular weight of the polystyrene, as determined by HPSEC, was 9500 with polydispersity of 1.2. 

Fig. 18. Proposed mechanism for the reactions of lithium -butyl amide and n-butylamine with [M(CN)r,NO]2 (M = Fe, Ru, Os).

This has been studied much less frequently and appears to be a rather more complex reaction. The first results obtained, for the butyl-lithium, styrene reaction in benzene have already been described. In a similar way the addition of butyllithium to 1,1-diphenylethylene shows identical kinetic behaviour in benzene (26). Even the proton extraction reaction with fluorene shows the typical one-sixth order in butyllithium (27). It appears therefore that in benzene solution at least, lithium alkyls react via a small equilibrium concentration of unassociated alkyl. This will of course not be true for reactions with polar molecules for reasons which will be apparent later. No definite information can be obtained on the dissociation process. It is possible that the hexamer dissociates completely on removal of one molecule or that a whole series of penta-mers, tetramers etc. exist in equilibrium. As long as equilibrium is maintained, the hexamer is the major species present and only monomeric butyllithium is reactive, the reaction order will be one-sixth. A plausible... 

The tobacco alkaloid anabasine (37) has been synthesized from 3-pyridyl-lithium (prepared from 3-bromopyridine and t-butyl-lithium) by reaction with A piperideine at —120 °C.46... 

To a slurry of 11.7 g (0.33 mole) of methyltriphenylphosphonium bromide in 150 ml of dry tetrahydrofuran at -35°C was added, over a 15-minute period, 20 ml (0.033 mole) of n-butyl lithium. The reaction mixture was stirred for one hour. To the reaction mixture at -35° to -40°C was added over a 10-minute period a solution of 5.7 g (0.0165 mole) of 3-chloro-5,6-bis(4-methoxyphenyl)-l,2,4-triazine in 50 ml of tetrahydrofuran. The reaction mixture was allowed to warm to ambient temperature and was stirred overnight. A solution of 1.05 g (0.0165 mole) of sodium carbonate in 50 ml of water was added dropwise to the reaction mixture which then was heated at reflux for three hours. The reaction mixture was cooled, poured over ice, and extracted with diethyl ether. The diethyl ether extract was washed with water, dried over anhydrous sodium sulfate, and concentrated. The concentrate was chromatographed over silica gel, with three fractions being collected. After evaporation of solvent, the third fraction solidified MP about 109°-113°C. 

The University of Kyoto, Japan, reports about a halogen-lithium exchange reaction of aryl bromides with butyl lithium (see Figure 5.20) [53,57]. The intermediate was trapped with an electrophile. The whole process was done under noncryogenic conditions at 0°C. 

The reaction of enol phosphates 84 with lithium -butyl tellurolate 85a, generated by reaction of -butyllithium with elemental tellurium, occurs rapidly to give the corresponding vinylic tellurides 86 (Scheme 51). Mixtures of (Z)- and ( )-enol phosphates afford the (Z)-vinylic telluride as the only product. ... 

Alkyl organo tellurium compounds, prepared from alkane- or arenetellurolates and alkyl halides, react with butyl lithium,. 9ec-butyl lithium, /ert.-butyl lithium, or phenyl lithium. The alkyl group bonded to the tellurium atom is cleaved from the tellurium and is present in solution as the alkyl lithium that can be used for further reactions. This tellurium-lithium exchange reaction is synthetically useful, whenever the alkyl halides cannot be converted to alkyl lithiums by other, more conventional halogen exchange reactions. The following exchange reactions were successfully carried out ... 

It was observed that ammonolysis of B(C2H,Si(R)H2)3 (Scheme 2, route A) requires basic catalysts such as n-butyl lithium. The reaction is performed in analogy to the potassium hydride-catalyzed cross-linking of cyclic silazanes described by Seyferth et al. [8]. Most probably, n-BuLi initially deprotonates the weak nucleophile ammonia with the formation of lithiiun amide and evaporation of n-butane. The stronger nucleophilic amide then replaces a silicon-bonded hydride, which subsequently deprotonates ammonia, leading to the evolution of molecular hydrogen. The silylamines that arise are not stable under the reaction conditions applied (refluxing solvent), and by fast condensation of ammonia the polymeric precursors form [6]. 

Bromothiophene is an important starting compound for the synthesis of other 3-substituted thiophenes. The very facile bromine-lithium exchange reaction proceeds almost qualitatively and the butyl bromide present in the solution does not interfere in subsequent reactions with reactive electrophilic reagents. The following procedures are examples of smooth reactions with the intermediary 3-lithiothiophene. 

Japanese chemists have now reported the alkylation of 1-lithiocy do propyl bromides, prepared by treatment of ge/n-dibromocyclopropanes with n-butyl-lithium, by reaction with an alkyl halide. They were able to prepare syn-1-methyl-anfi-7-bromonorcarane (3) as the exclusive product by addition of methyl iodide to (2), prepared essentially by Seyferth s procedure. As applied to other g-ew-dibromocyclopropanes, the reaction is usually stereoselective rather... 

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