Alkyl halide treatment

The alkyl halides in the presence of a strong base can be used for fiber etherification. 

Reactions of fiber with crotyl chloride, methyl iodide and butyl chloride have led to an improvement in dimensional stability. Decay resistance has also been investigated for wood treated with fatty dialkyldimethylammonium chlorides and bromides. Treated wood showed good resistance against brown rot fungi [40]. 

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Several authors have demonstrated the feasibility of the alkylation of a MSMA substrate to obtain the homologous RSMA via reaction of the corresponding a-silylcarbanion with an alkyl halide. Treatment with LDA of (allyl)(pyrrazolylmethyl) silane gives a carbanion that on trapping with methyl iodide, leads to the unique formation of the corresponding RSMA derivative without traces of compounds that could have resulted from the allylic system. However, when. v-butyllithium is used instead of LDA, partial methylation of this system also occurs.66... 

A convenient synthesis of 2-amino-iV-alkylbenzylamines 196 by direct mono alkylation of 2-aminobenzylamine has been achieved by a potassium ferZ-butoxide/alkyl halide treatment of the 9-borabicyclo[3.3.1]nonane (9-BBN) aminoborane derivative 195. This method relies on formation of a stable chelate, which serves in the dual roles of protecting and activating the amino group (Scheme 34) <1998TL2643>. A similar approach has been used for selective mono-N-alkylation of 1,8-diaminonaphthalene <1997JOC6682> and amino alcohols <2004OL3549>. 

The alkylation at the ortho carbon is possible by the reaction of chelate complexes with Grignard reagents, organolithium reagents in the presence of PPhs, or alkyl halides. o-Methylbenzaldehyde was prepared via the formation of a Schiff base complex 423 and its reaction with MeLi [178]. The ortho alkylation is possible even with alkyl halides. Treatment of acetanilide (424) with 3 equivalents of... 

The mono-alkyl C-substituted derivatives of ethyl acetoacetate upon treatment with sodium ethoxide and another molecule of alkyl halide afford the di-alkyl C-substituted products... 

A special problem arises in the preparation of secondary amines. These compounds are highly nucleophilic, and alkylation of an amine with alkyl halides cannot be expected to stop at any specifle stage. Secondary amides, however, can be monoalkylated and lydrolyzed or be reduced to secondary amines (p. 11 If.). In the elegant synthesis of phenyl- phrine an intermediate -hydroxy isocyanate (from a hydrazide and nitrous acid) cyclizes to pve an oxazolidinone which is monomethylated. Treatment with strong acid cleaves the cyclic irethan. 

The acidity of acetylene and terminal alkynes permits them to be converted to their conjugate bases on treatment with sodium amide These anions are good nucleophiles and react with methyl and primary alkyl halides to form carbon-carbon bonds Secondary and tertiary alkyl halides cannot be used because they yield only elimination products under these conditions... 

Sulfides compounds of the type RSR are prepared by nucleophilic substitution reac tions Treatment of a primary or secondary alkyl halide with an alkanethiolate ion (RS ) gives a sulfide... 

Treatment of the anion of diethyl malonate with alkyl halides leads to alkylation at C 2... 

IV-Methylated pyridazinones can be obtained from 3,6-dialkoxypyridazines by treatment with alkyl halides or dialkyl sulfates. Methyl iodide and dimethyl sulfate are most frequently used. According to the proposed mechanism, an intermediate quaternary pyridazinium salt is formed, followed by elimination of a group R from the alkoxy group. At higher temperature, l,2-dimethylpyridazine-3,6(l//,2//)-dione is formed with dimethyl sulfate. 

Pyrrolethiols, readily obtained from the corresponding thiocyanates by reduction or treatment with alkali, rapidly oxidize to the corresponding disulfides. They are converted into thioethers by reaction with alkyl halides in the presence of base. Both furan- and thiophene-thiols exist predominantly as such rather than in tautomeric thione forms. 

Electrophilic attack on the sulfur atom of thiiranes by alkyl halides does not give thiiranium salts but rather products derived from attack of the halide ion on the intermediate cyclic salt (B-81MI50602). Treatment of a s-2,3-dimethylthiirane with methyl iodide yields cis-2-butene by two possible mechanisms (Scheme 31). A stereoselective isomerization of alkenes is accomplished by conversion to a thiirane of opposite stereochemistry followed by desulfurization by methyl iodide (75TL2709). Treatment of thiiranes with alkyl chlorides and bromides gives 2-chloro- or 2-bromo-ethyl sulfides (Scheme 32). Intramolecular alkylation of the sulfur atom of a thiirane may occur if the geometry is favorable the intermediate sulfonium ions are unstable to nucleophilic attack and rearrangement may occur (Scheme 33). 

Alkyl fluorides have been prepared by reaction between elementary fluorine and the paraffins, by the addition of hydrogen fluoride to olefins, by the reaction of alkyl halides with mercurous fluoride, with mercuric fluoride, with silver fluoride, or with potassium fluoride under pressure. The procedure used is based on that of Hoffmann involving interaction at atmospheric pressure of anhydrous potassium fluoride with an alkyl halide in the presence of ethylene glycol as a solvent for the inorganic fluoride a small amount of olefin accompanies the alkyl fluoride produced and is readily removed by treatment with bromine-potassium bromide solution. Methods for the preparation of alkyl monofluorides have been reviewed. ... 

Most of the alkylations were carried out by adding a solution of 3,3-ethylenedioxypregna-5,16-dien-20-one in tetrahydrofuran to a solution of lithium in liquid ammonia to the point of color discharge. Treatment with the alkyl halide then furnishes the corresponding 17a-alkyl derivative (10). After hydrolysis of the 3-ketal group, 17a-methyl-, ethyl-, propyl-, butyl-, hexyl-, octyl-, allyl-, and benzylprogesterones are obtained. 

Various sources of fluoride ion have been investigated, of which highly nucleophilic tetraalkylammonium fluorides ate the most effective Thuf, fluoro alkyl halides and N (fluoroalkyl)amines are efficiently synthesized by treatment of the corresponding trifluoromethanesulfonic esters with tetrabutylammonium fluoride trihydrate in aprotic solvents [5fl] (equation 34) The displacement reactions proceed quantitatively at room temperature within seconds, but tail with hydrogen fluoride-pyridine and give reasonable yields only with hydrogen fluo ride-alkylamine reagents... 

One of the advantages of the enamine alkylation reaction over direct alkylation of the ketone under the influenee of strong base is that the major product is the monoalkylated derivative 29,32). When dialkylation is observed, it occurs at the least substituted carbon in contrast to alkylation with base, where the a-disubstituted product is formed. Dialkylation becomes the predominant reaction when a strong organic base is added and an excess of alkyl halide is used (29). Thus 1-N-pyrrolidino-l-cyclo-hexene (28) on treatment with two moles of allyl bromide in the presence of ethyl dicyclohexylamine (a strong organic base which is not alkylated under the reaction conditions) gave a 95 % yield of 2,6-diallylcyclohexanone (29). 

Treatment of 1,3-dicarbonyl eompounds with two equivalents of strong base ean give a dianion that will react selectively with alkyl halides. For example, ethyl acetoacetate reacts first with NaH to form an enolate, and then with n-BuLi to form a dianion. This then adds t-PrI. 

Variations and Improvements on Alkylations of Chiral OxazoUnes Metalated chiral oxazolines can be trapped with a variety of different electrophiles including alkyl halides, aldehydes,and epoxides to afford useful products. For example, treatment of oxazoline 20 with -BuLi followed by addition of ethylene oxide and chlorotrimethylsilane yields silyl ether 21. A second metalation/alkylation followed by acidic hydrolysis provides chiral lactone 22 in 54% yield and 86% ee. A similar... 

Furthermore they claimed that the dichloromethyhndolenine 17 could be converted into the quinohne 18 by hot ethanolic sodium ethoxide. They also reported other similar cases of ring expansion of the dichloromethyl bases, with loss of hydrogen chloride, on further treatment with sodium ethoxide (cf. ref. 67). They considered that chloroform acted like a simple alkyl halide giving jS-alkylation of the... 

Alkylation at the ind-N of l,2,3,4-tetrahydro-j8-carbolines has been carried out with alkyl halide after treatment with sodamide in the usual manner. Cyanoethylation of a p /r-V-substituted tetrahydro-jS-carboline in the presence of Triton B yields the corresponding 9-cyanoethyl derivative. Similarly, treatment of p / -V-methyl-l,2,3,4,4a,9b-hexahydro-y-carboline with sodamide, followed by benzyl chloride, leads to the ind-A -benzyl-substituted derivatives. l-Oxo-l,2,3,4-tetrahydro-j8-carboline yields the ind-A -methyl derivative directly with dimethyl sulfate.Prolonged treatment with sodium hydride, followed by methyl iodide, yields the 2,9-dimethyl derivative. Heating with sodium hydride in acetone followed by the addition of dimethyl sulfate gives rise to the ind-V-methyl derivative. ... 

The Arbuzov reaction,also called the Michaelis-Arbuzov reaction, allows for the synthesis of pentavalent alkyl phosphoric acid esters 4 from trivalent phosphoric acid esters 1 (Z,Z = R,OR) by treatment with alkyl halides 2. 

Another type of Grignard reaction is the alkylation with alkyl halides. Upon treatment of a Grignard reagent RMgX with an alkyl halide 5, a Wwrtz-like coupling reaction takes place. 

A common method for the preparation of alkyl cyanide 2 is the treatment of corresponding alkyl halides 1 with cyanide. The corresponding reaction with aromatic substrates is called the Rosenmund-von-Braun reaction. 

Phosphorus ylides like 1 can be prepared by various routes. The most common route is the reaction of triphenylphosphine 5 with an alkyl halide 6 to give a triphenylphosphonium salt 7, and treatment of that salt with a base to give the corresponding ylide 1 ... 

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