Benzylic generation

Temporarily cap these hydroxyl positions (e.g., benzylation) generating a highly electron-rich carbohydrate residue [step (2), capping],... 

Addition of several organomercury compounds (methyl, aryl, and benzyl) to conjugated dienes in the presence of Pd(II) salts generates the ir-allylpalladium complex 422, which is subjected to further transformations. A secondary amine reacts to give the tertiary allylic amine 423 in a modest yield along with diene 424 and reduced product 425[382,383]. Even the unconjugated diene 426 is converted into the 7r-allyllic palladium complex 427 by the reaction of PhHgCI via the elimination and reverse readdition of H—Pd—Cl[383]. 

Nearly all uses and appHcations of benzyl chloride are related to reactions of the active haUde substituent. More than two-thirds of benzyl chloride produced is used in the manufacture of benzyl butyl-phthalate, a plasticizer used extensively in vinyl flooring and other flexible poly(vinyl chloride) uses such as food packaging. Other significant uses are the manufacture of benzyl alcohol [100-51-6] and of benzyl chloride-derived quaternary ammonium compounds, each of which consumes more than 10% of the benzyl chloride produced. Smaller volume uses include the manufacture of benzyl cyanide [140-29-4], benzyl esters such as benzyl acetate [140-11-4], butyrate, cinnamate, and saUcylate, benzylamine [100-46-9], and benzyl dimethyl amine [103-83-8], and -benzylphenol [101-53-1]. In the dye industry benzyl chloride is used as an intermediate in the manufacture of triphenylmethane dyes (qv). First generation derivatives of benzyl chloride are processed further to pharmaceutical, perfume, and flavor products. 

NaH, THF, BnBr, Bu4N I, 20°, 3 h, 100%. This method was used to protect a hindered hydroxyl group. Increased reactivity is achieved by the in situ generation of benzyl iodide. ... 

Benzyl and allyl alcohols which can generate stabilized caibocations give Friedel-Crafts alkylation products with mild Lewis acid catalysts such as scandium triflate. ... 

Carbocations can also be generated during the electrolysis, and they give rise to alcohols and alkenes. The carbocations are presumably formed by an oxidation of the radical at the electrode before it reacts or diffuses into solution. For example, an investigation of the electrolysis of phenylacetic acid in methanol has led to the identification of benzyl methyl ether (30%), toluene (1%), benzaldehyde dimethylacetal (1%), methyl phenylacetate (6%), and benzyl alcohol (5%), in addition to the coupling product bibenzyl (26%). ... 

NOTE - Petrochemical plants also generate significant amounts of solid wastes and sludges, some of which may be considered hazardous because of the presence of toxic organics and heavy metals. Spent caustic and other hazardous wastes may be generated in significant quantities examples are distillation residues associated with units handling acetaldehyde, acetonitrile, benzyl chloride, carbon tetrachloride, cumene, phthallic anhydride, nitrobenzene, methyl ethyl pyridine, toluene diisocyanate, trichloroethane, trichloroethylene, perchloro-ethylene, aniline, chlorobenzenes, dimethyl hydrazine, ethylene dibromide, toluenediamine, epichlorohydrin, ethyl chloride, ethylene dichloride, and vinyl chloride. 

Lead tetrafluoride, generated in situ from lead dioxide and hydrogen fluonde, can replace benzylic hydrogen by fluonne [3] Under sirmlar conditions phenol is simultaneously oxidized to 4,4-difluoro-2,5-cyclohexadienone [4 (equations 3 and 4)... 

Both methyltriethylphosphonium fluoride and methyltributylphospho-nium fluoride have been prepared The latter generates benzyl fluoride from benzyl chloride in 80% yield and ethyl fluoroacetate from ethyl bromoacetate in 53% yield Methyltnbutylphosphonium fluoride converts 1-bromododecane to a 50 50 mixture of 1-fluorododecane and 1-dodecene Methyltnbutylphosphonium fluoride also quantitatively forms styrene from 1-bromo-1-phenylethane [26] Methyl-tnbutylphosphonium fluonde is the reagent of choice for the conversion of N,N dimethylchloroacetamide to its fluoride, but it is not able to convert chloro-acetonitnle to fluoroacetomtrile Methyltnbutylphosphonium fluoride changes chloromethyl octyl ether to the crude fluoromethyl ether in 66% yield The stereoselectivity of methyltnbutylphosphonium fluoride is illustrated by the reac tions of the 2-tert-butyl-3-chlorooxiranes [27] (Table 2)... 

Conversion of l,6-anhydro-4-0-benzyl-2 deoxy 2-fluoro-p-D-glucopyranose to the corresponding oxo derivative is earned out by ruthenium tetroxide generated in situ from ruthenium dioxide [54] (equation 49)... 

Pentafluorophenylnitrene generated by the photolysis of pentafluorophenyl-azide in toluene at 25 gives pentafluoroaniline and benzyl-substituted anilines At low temperatures (-78 to -196 °C), perfluoroazobenzene also is formed [7] (equation 8)... 

The stereospecific generation of enamines by -elimination reactions (187) and a vinylogous elimination, which leads to a dienamine (188), have been reported. The loss of an a substituent from a tertiary amine is seen in the generation of enamines by elimination of hydrogen cyanide from benzylic a-aminonitriles (189,190). 

Alkyl radicals can be obtained by abstraction of a hydrogen atom from an alkyl group by another radical. This method was utilized for the generation of benzyl radicals from toluene with iert-butoxy radical obtained on heating di- er -butyl peroxide. BenzoyP and carboxymethyP radicals have also been obtained by this method. The reaction gives rise to a complex mixture of products and therefore is of rather limited use. 

The reaction of benzyl radicals wdth several heterocyclic compounds W as more extensively studied by Waters and Watson, " - who generated benzyl radicals by decomposing di-tert-butyl peroxide in boiling toluene. The products of the reaction with acridine, 5-phenyl-acridine, 1 2- and 3 4-benzacridine, and phenazine were studied. Acridine gives a mixture of 9-benzylacridine (17%) (28) and 5,10-dibenzylacridan (18%) (29) but ho biacridan, w hereas anthracene gives a mixture of 9,10-dibenzyl-9,10-dihydroanthracene and 9,9 -dibenzyl-9,9, 10,10 -tetrahydrobianthryl. This indicates that initial addition must occur at the meso-carbon and not at the nitrogen atom. (Similar conclusions were reached on the basis of methylations discussed in Section III,C.) That this is the position of attack is further supported by the fact that the reaction of benzyl radicals with 5-... 

The mechanism of benzylic bromination is similar to that discussed in Section 10.4 for allylic bromination of alkenes. Abstraction of a benzylic hydrogen atom generates an intermediate benzylic radical, which reacts with Br2 to yield product and a Br- radical that cycles back into the reaction to carry on the chain. The Br2 necessary for reaction with the benzylic radical is produced by a concurrent reaction of HBr with NBS. 

Tetraphenyl-3//-azepine (2) is formed by the action of sodium hydride on 1-benzyl-2,4,6-triphenylpyridinium tetrafluoroborate (1) in refluxing toluene.37 The 3//-azepine. which arises by attack of the carbanion, generated at the benzylic carbon, at the 2-position of the pyridine ring, is also formed, unexpectedly, in the reaction of the pyridinium tetrafluoroborate with the enolate of ethyl 2-methyl-3-oxobutanoate. 

Deoxygenation of benzyl nitrosoformate, generated by retro-Diels-Alder reaction of its [4 + 2] cycloadduct 27 with 9,10-dimethylanthracene, with triphenylphosphane in anhydrous benzene yields the unstable benzyl 1//-azepine-1-carboxylate (28).143... 

Benzyl-type carbanions and their metallo compounds, derived from aromatic or hetero-aromatic precursors, bearing carbon- or hetero-substituents, are readily available with variable substitution patterns due to their mesomeric stabilization (see Section 1.3.2.2)2. Even dicarbanions are accessible without difficulty3,4. The equilibrium acidities of many aromatic hydrocarbons have been determined5-7. The acidities of a-hetero-substituted toluenes8 are similar to those of the corresponding allylic compounds and can usually be generated by the same methods. 

Ester enolates which contain the chiral information in the acid moiety have been widely used in alkylations (see Section D.1.1.1,3.) as well as in additions to carbon-nitrogen double bonds (sec Section D.1.4.2.). Below are examples of the reaction of this type of enolate with aldehydes720. The (Z)-enolate generated from benzyl cinnamate (benzyl 3-phenylpropcnoate) and lithium (dimethylphenylsilyl)cuprate affords the /h/-carboxylic acid on addition to acetaldehyde and subsequent hydrogenolysis, The diastereoselectivity is 90 10. 

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