As alkylating agents

Esters of /i-toluenesulphonic acid, which are of great value as alkylating agents, may be prepared by interaction of p-toluenesulphonyl chloride and the alcdiol in the presence of sodium hydroxide solution or of pyridine, for example ... 

The reactivity of sulfathiazoles has been reviewed (65). Methylation in alkaline solution with dimethyl sulfate gives only the ring methylated derivative (85). Mixtures of products are obtained with diazomethane as alkylating agent (see p. 37). Other alkyl halides in aqueous alkali lead also to ring-alkylated products (85. 251, 650. 669-671). 

The use of epoxides as alkylating agents for diethyl malonate provides a useful route to y lactones Wnte equations illustrating such a sequence for styrene oxide as the starting epoxide Is the lactone formed by this reaction 3 phenylbutanohde or is it 4 phenylbutanohde ... 

The methylation of N-methyl derivatives of maleic hydrazide gives in general O-alkylated products. The opposite results are obtained with benzyl halides as alkylating agents. In this case the O-benzyl derivative (71) is formed, which is then further benzylated to the lV,0-dibenzyl derivative (72). When ethyl chloroacetate is used, the direction of alkylation is dependent on pH. At pH above 8, O-alkylation occurs at pH below 8, N-alkylation takes place exclusively in neutral and acidic solutions only IV-alkylated products are formed. 

The antitumor activity displayed by the mitosanes and many synthetic aziridines stems from their ability to act as alkylating agents which chemically modify (crosslink) DNA. For this reason, a large number have been screened for antitumor activity, the mechanism of which has been the subject of considerable research effort <75CJC289l). An excellent account of the broad spectrum of biological properties of a multitude of compounds containing the aziridinyl moiety has been published [Pg.93]

Of the many methods which have been published so far for the substitution of existing crowns, probably the most straightforward are Friedel-Crafts alkylation or acylation reactions. Cygan, Biernat and Chadzynski have reported the successful di-t-butylation of dibenzo-24-crown-8 using t-butanol as alkylating agent s . The crown was heated at 100° for 4 h in the presence of excess t-butanol and 85% phosphoric acid. The product was obtained as a crystalline (mp 52—74°) solid in 93% yield. The alkylated crowns are presumably a mixture of isomers substituted once in each ring as illustrated in Eq. (3.14). 

Ketones and alcohols are frequently used as alkylating agents Ketones often condense with two molecules of an aromatic compound through an alcohol intermediate [79, 20, 21] T,r,I -Trifluoroacetophenone and aniline afford 1,1 bis(4-ammophenyl) 1 phenyl 2,2,2-trifluoroethane [27] (equation 14)... 

The behavior of such activated halides as alkylating agents under Friedel-Crafts conditions expands the scope of the synthesis. Aluminum chloride enhances the electrophilic character of the a,/S-unsaturated carbonyl system and permits the nucleophilic attachment of the aromatic addendum (Y ) to the carbon bearing the positive charge, with displacement of halogen [Eq. (5)]. Thus,... 

An important application of the potential for bis-alkylation is the use of a dihalide 7 as alkylating agent. This variant allows for the synthesis of cyclic compounds 8 by this route, mainly five- to seven-membered ring compounds have been prepared ... 

As alkylating agents may for example be used alkyl halides, dialkyl sulfates, alkyl sulfonates and epoxides. Aryl halides and vinylic halides do not react. 

Furthermore, a substitution of the amino group is possible. An important application of Mannich bases 4 is their use as alkylating agents ... 

As alkylating agent an alkyl halide, alkyl tosylate or dialkyl sulfate is used in most cases the latter type of reagent is often used in the preparation of methyl and ethyl ethers by employing dimethyl sulfate and diethyl sulfate respectively. Dimethyl sulfate is an excellent methylating agent, but is acutely toxic as well as carcinogenic." ... 

Monochloroparaffins in this range may be dehydrochlorinated to the corresponding monoolefms and used as alkylating agents for the production of biodegradable detergents. Alternatively, the monochloroparaffins are used directly to alkylate benzene in presence of a Lewis acid catalyst to produce alkylates for the detergent production. These reactions could be illustrated as follows ... 

Isobutylene could be dimerized in the presence of an acid catalyst to diisobutylene. The product is a mixture of diisobutylene isomers, which are used as alkylating agents in the plasticizer industry and as a lube oil additive (dimerization of olefins is noted in Chapter 3). 

Epoxides are found in thousands of biological molecules and constitute vital functional entities. They can impart localized structural rigidity, confer cytotoxicity through their role as alkylating agents, or act as reactive intermediates in complex synthetic sequences. The widespread occurrence of epoxides is contrasted by only a handful of aziridines that are known to date. In this chapter we would like to introduce the different mechanisms by which enzymes produce epoxides. 

Apart from the alkyl halide-Lewis acid combination, two other sources of carbo-cations are often used in Friedel-Crafts reactions. Alcohols can serve as carbocation precursors in strong acids such as sulfuric or phosphoric acid. Alkylation can also be effected by alcohols in combination with BF3 or A1C13.37 Alkenes can serve as alkylating agents when a protic acid, especially H2S04, H3P04, and HF, or a Lewis acid, such as BF3 and A1C13, is used as a catalyst.38... 

Di Valentin, C. Freccero, M. Zanaletti, C. Sarzi-Amade, M. o-Quinone methide as alkylating agent of nitrogen, oxygen, and sulfur nucleophiles. The role of H-bonding and solvent effects on the reactivity through a DFT computational study, j. Am. Chem. Soc. 2001, 123, 8366-8377. 

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