Carboxylate salts, reaction with

Sec. 21.5) from acid chlorides by reaction with carboxylate salts... 

B. Reactions with Carboxylate Salts, Acid Chlorides, and Acid Anhydrides to give Ketones... 

Especially for large-scale work, esters may be more safely and efficiently prepared by reaction of carboxylate salts with alkyl halides or tosylates. Carboxylate anions are not very reactive nucleophiles so the best results are obtained in polar aprotic solvents45 or with crown ether catalysts.46 The reactivity order for carboxylate salts is Na+ < K+ < Rb+ < Cs+. Cesium carboxylates are especially useful in polar aprotic solvents. The enhanced reactivity of the cesium salts is due to both high solubility and minimal ion pairing with the anion 47 Acetone is a good solvent for reaction of carboxylate anions with alkyl iodides48 Cesium fluoride in DMF is another useful... 

As noted in the preceding section, one of the most general methods of synthesis of esters is by reaction of alcohols with an acyl chloride or other activated carboxylic acid derivative. Section 3.2.5 dealt with two other important methods, namely, reactions with diazoalkanes and reactions of carboxylate salts with alkyl halides or sulfonate esters. There is also the acid-catalyzed reaction of carboxylic acids with alcohols, which is called the Fischer esterification. 

Cerium reagents have also been found to give improved yields in the reaction of organolithium reagents with carboxylate salts to give ketones. 

The synthesis of cobalt meso-diphenyl corrolates has also been reported [31]. The synthetic procedure involves the acidic condensation of 3,4-dimethyl-2-(a-hydroxybenzyl)pyrrole-5-carboxylic acid with 3,3, 4,4 -tetramethyl dipyrro-methane, followed by reaction with cobalt salts. The reaction afforded a mixture of two isomers Co(5,15-OMDPC)PPh3 and Co(5,10-OMDPC)PPh3. The formation of this latter isomer has been explained by the high tendency of self condensation of the starting pyrrole under the reaction conditions, 2-(a-hydroxybenzyl)meso-phenyl dipyrromethane can be formed. This species would afford the Co(5,10-OMDPC)PPh3 by further condensation with the dipyrromethane unit present in excess in the reaction mixture. 

Reactions with Diazonium Salts, Organic Halides, and Carboxylic Acids... 

Reaction of carboxylate salts with chloromethyl ethers (ROCH2CI) takes place under conditions similarly used to protect hydroxyl functions [Scheme 6.82].186 In the absence of acid, the resultant acetal esters display reactivity typical of alky esters. 

Oxidation of C—bonds by copper ion catalyzed reaction with an organic peroxy ester (the Kha-rasch-Sosnovsky reaction) was at one time very popular for allylic oxidation and has been thoroughly reviewed. The reaction is usually carried out by dropwise addition of peroxy ester (conunonly r-butyl peracetate or r-butyl perbenzoate) to a stirred mixture of substrate and copper salt (0.1 mol % commonly copper(I) chloride or bromide) in an inert solvent at mildly elevated temperature (60-120 C). The mechanism involves three steps (i) generation of an alkoxy radical (ii) hyttogen atom abstractitm and (iii) radical oxidation and reaction with carboxylate anion (Scheme 11). 

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