In alkylation reactions

Magnesium ethylate is used as a drying agent for organic solvents, as an intermediate for the manufacture of organomagnesium and other organic products, as catalyst in the Tishchenko (85) and other reactions (86—91), in the condensation of esters (92), in alkylation reactions, and in polymeri2ations (84,91). 

Tbifluoromethylmercaptides can be used as nucleophilic reagents in alkylation reactions [80, 81] (equation 72)... 

The illumination of enamines as general activa ting derivatives of ketones in alkylation reactions also threw light on their special usefulness for controlling alkylations (3), particularly in the formation of monosubstituted cyclohexanones. Thus 2-methylcyclohexanone could be obtained in 80% yield from the pyrrolidine enamine of cyclohexanone, and further alkylation, which required more drastic conditions, gave only 2,6-dimethylcyclo-hexanone (1,237). 

The chelated lithium anions 1 and 2, derived from enantiomerically pure tetrahydroisoquino-line-amidines or -oxazolines, exhibit high induced stereoselectivity in alkylation reactions (Section D.l.1.1.1.3.1.). 

Organomagnesium and organolithium compounds are strongly basic and nucleophilic. Despite their potential to react as nucleophiles in SN2 substitution reactions, this reaction is of limited utility in synthesis. One limitation on alkylation reactions is competition from electron transfer processes, which can lead to radical reactions. Methyl and other primary iodides usually give the best results in alkylation reactions. 

Organolithium reagents in which the carbanion is delocalized are more useful than alkyllithium reagents in alkylation reactions. Allyllithium and benzyllithium reagents can be alkylated and with secondary alkyl bromides and a high degree of inversion of configuration is observed.78... 

The manufacture of fertilizers was discussed in Chapter 14. Phosphate rock is digested with sulfuric acid to convert CaC03 into a more soluble form that contains a higher percentage of phosphorus. Sulfuric acid is used as a catalyst in alkylation reactions, petroleum refining, manufacture of detergents, paints, dyes, and fibers, and other processes. It is also used as the electrolyte in the lead-acid battery that is used in automobiles. Sulfuric acid is an enormously important chemical commodity that it would be hard to do without. 

As with the above pyrrolidine, proline-type chiral auxiliaries also show different behaviors toward zirconium or lithium enolate mediated aldol reactions. Evans found that lithium enolates derived from prolinol amides exhibit excellent diastereofacial selectivities in alkylation reactions (see Section 2.2.32), while the lithium enolates of proline amides are unsuccessful in aldol condensations. Effective chiral reagents were zirconium enolates, which can be obtained from the corresponding lithium enolates via metal exchange with Cp2ZrCl2. For example, excellent levels of asymmetric induction in the aldol process with synj anti selectivity of 96-98% and diastereofacial selectivity of 50-200 116a can be achieved in the Zr-enolate-mediated aldol reaction (see Scheme 3-10). 

Table 1.2. Yield of Products in Alkylation Reaction of Phenol by Styrene...

Scheme 10.10. Radical mechanism in alkylation reactions with alkyl halides.

Small samples may readily be distilled with little decomposition, while large samples decompose significantly during (list, nation. The undistilled material may be satisfactory for use in alkylation reactions without purification. The checkers have (bund that 200 g. quantities of the product can reprodticibly lie distilled at approximately 1 mm. The reported physical constants for benzyl chloromethyl ether are b.p. 96-98° (9.5 imn.)2, n n 1.5264-1.5292. i2... 

The indole anion is resonance stabilized, with negative charge localized mainly on nitrogen and C-3. It can now participate as a nucleophile, e.g. in alkylation reactions. However, this can lead to iV-alkylation or C-alkylation at C-3. Which is the predominant product depends upon a number of... 

Hydroxamic acids undergo facile nucleophilic Ai-arylation with activated aryl halides such as 31 (equation 22). While hydroxamates are known to be ambident nucleophiles in alkylation reactions, arylation of hydroxylamines results exclusively in Ai-substituted hydroxamates of type 32 (equation 22)". ... 

In this review, we will initially describe the role of Bi(III) salts as activators for a-donors. In particular, benzyl and propargyl alcohols will be presented as mild electrophiles in alkylation reactions. In addition, we will show the versatility of Bi(III) salts and give a short overview of Bi(III)-catalyzed hydroarylation and hydroalkynylation reactions [23]. Besides our own results, which primarily focus... 

The regio- and stereoselectivity of enolate formation are essential for the control of alkylation reactions. The regioselectivity of ketone deprotonation has been extensively investigated and this important step in alkylation reactions has been discussed in many reviews (e.g., refs 1-4, 71) and textbooks (e.g., refs 5, 6). Therefore, this topic will be discussed here only in general terms. 

Some of the /i-lactams used in alkylation reactions have themselves been prepared by asymmetric synthesis before their use as synthetic intermediates for the preparation of enantiomerically... 

The relatively high diastereoselectivities observed in alkylation reactions are best explained by invoking the following ... 

Whereas branched ketimines are metalated at the less substituted carbon, metalation and alkylation of unsymmetric imines leads to regioisomers2,4,27. For this reason, only symmetrical ketones and unsymmctrical ketones with one substituent having no a-hydrogens have been applied in alkylation reactions via imines (see Table 4). 

Butenes are used extensively in gasoline production to produce high-octane gasoline compounds. In alkylation reactions, butenes combine with isobutane to produce branched gasoline-range compounds (see Butane). Isooctane can be produced by dimerization of isobutene in the presence of sulfuric acid. Dimerization is the combination of a molecule with itself to produce a molecule called a dimer. The dimer has exactly twice the number of atoms in the original molecule. Therefore the dimerization of isobutene produces two dimers with the formula C H,... 

Uen/.yl chloromethyl other is useful for the introduction of a potential hydroxy methyl group in alkylation reactions. Hill and Koaclf1 were the lirBt to use this method and found it... 

There are nitrogen anions that are useful in alkylation reactions, but they are derived from carboxamides and sulfonamides rather than amines. Two examples are given here to illustrate the synthesis of a primary and a secondary amine (also see Section 18-IOC) ... 

Open-chain (acyclic) dialkylhalonium ions of the type R2X+ (X = Cl, Br, I) were unknown until the 1960s, as were alkylarylhalonium ions (ArRX+). Realization of their possible role as intermediates in alkylation reactions of haloalkanes and -arenes has followed their preparation and study.333... 

The reactivity of haloalkanes in alkylation reactions also decreases with increasing chain length. In general, syntheses of salts with short alkyl substituents are more complex due to the low boiling points of the haloalkanes. The most frequently used halide salt in this field, l-ethyl-3-methylimidazolium chloride ([EMIM] Cl), is typically synthesized in an autoclave with the chloroethane cooled to below its boiling point (12 °C) before addition. 

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