Carboxylate anion reaction with methyl alcohol

Methyl esters undergo trans-esterification with the quaternary ammonium salts at high temperature and the reaction has been used with some effect for the preparation of, for example, n-butyl esters by heating the methyl ester with tetra-n-butylammo-nium chloride at 140°C [31]. Optimum yields (>75%) are obtained in HMPA or in the absence of a solvent. A two-step (one-pot) trans-esterification under phase-transfer catalysed conditions in which the carboxylate anion generated by initially hydrolysis of the ester is alkylated has been reported for Schiff s bases of a-amino acids [32] and for A-alkoxycarbonylmethyl [1-lactams [33]. Direct trans-esterification of methyl and ethyl esters with alcohols under basic catalytic conditions occurs in good yield in the presence of Aliquat [34, 35]. 

UV irradiation of aq solns of TNT has yielded a mixt of products, 15 of which have been identified (Ref 85). The methyl group has undergone reaction in all of these compds (to alcohol, aldehyde, carboxyl, or their derivatives). A nitro group has reacted in some cases this is always ortho and never para to the methyl group. Reaction of TNT which involve the intermediacy of anion (D), such as the reaction with 4-nitroso-... 

A further dependence of the selectivity between different nucleophiles on the stability and reactivity of carbocations was found by Richard and Amyes in a study of reactions of alcohols and carboxylate anions with -substituted a-trifluoromethyl benzyl cations (75, X = Me, OMe, SMe, N(Me)CH2CF3, and NMe2) monitored using the azide clock.305 Apart from the methyl-substituted substrate, for which the reactions approached diffusion control,... 

Tertiary benzylic nitriles are useful synthetic intermediates, and have been used for the preparation of amidines, lactones, primary amines, pyridines, aldehydes, carboxylic acids, and esters. The general synthetic pathway to this class of compounds relies on the displacement of an activated benzylic alcohol or benzylic halide with a cyanide source followed by double alkylation under basic conditions. For instance, 2-(2-methoxyphenyl)-2-methylpropionitrile has been prepared by methylation of (2-methoxyphenyl)acetonitrile using sodium amide and iodomethane. In the course of the preparation of a drug candidate, the submitters discovered that the nucleophilic aromatic substitution of aryl fluorides with the anion of a secondary nitrile is an effective method for the preparation of these compounds. The reaction was studied using isobutyronitrile and 2-fluoroanisole. The submitters first showed that KHMDS was the superior base for the process when carried out in either THF or toluene (Table I). For example, they found that the preparation of 2-(2-methoxyphenyl)-2-methylpropionitrile could be accomplished h... 

Carbonylation with iron carbonyls parallels that of cobalt carbonyls. Benzylic chlorides and bromides are carbonylated with Fe(CO)5 in the presence of base. Esters are realized when carbonylation is performed in alcohols under 1 atm of CO with catalytic amounts of iron pentacarbonyl415. Under phase transfer conditions, two predominant routes are available. With catalytic amounts of iron under a CO atmosphere and strongly basic conditions, the carboxylic acids are realized in reasonable yields415,416, whereas mild bases [Ca(OH)2l, stoichiometric amounts of iron carbonyl and the omission of CO give dibenzyl ketones417. In at least a few cases, it is possible to prepare unsymmetrical methyl benzyl ketones418, des Abbayes and coworkers have observed the formation of acyltetracarbonyl anion (52) under the reaction conditions, and have proposed the catalytic cycle in Scheme 8 for the ketone formation418. 

Two series of new polyphosphazenes were prepared by derivatization of preformed poly(methylphenylphosphazene), [Me(Ph)PN]p. This Involved Initial deprotonatlon of part of the methyl substituents with n-BuLi followed by treatment of the intermediate anion with carbon dioxide or with fluorinated aldehydes or ketones. With appropriate workup procedures, either carboxylic acid, ester, carboxylate salt, or fluorinated alcohol derivatives were obtained. These reactions and the characterization of the products are discussed In this paper. Related derivatization reactions are also discussed. 

---