Conversion into esters

Perhaps the most useful reaction of carboxylic acids is their conversion into esters. There are many methods for accomplishing the transformation, including the S -2 reaction of a carboxylate anion with a primary alkyl halide that we saw in Section 11.3. 

Oxidation of ketones with hydrogen peroxide or with a peroxyacid, RC020H (cf. p. 330) results ia their conversion into esters ... 

The preparation of such chlorides from the corresponding carboxylic acids and their conversion into esters or amides have been covered briefly in Section 28.1.2. Other reported reactions are exemplified here. 

Enantiomers of 3,3-dimethyl-2-butanol and other alcohols were separated by preparative GC on OV-type phases after their conversion into esters of N-TFA-L-alanyl [42]. 

As far as ring hydroxy groups are concerned, the conversion into esters and ethers has been carried out only on 3-hydroxyphenothia-zines, readily available from phenothiazones. Thus, 3-acetoxy-phenothiazine was prepared on acetylating 3-hydroxyphenothiazine with acetic anhydride. ... 

By far the most important oxidation of ethers is their conversion into esters and lactones. Only a few reagents are capable of such a transformation ozone [110], chromium trioxide [539, 586], zinc dichromate [660], potassium permanganate [855], zinc permanganate [898], benzyltriethylam-monium permanganate [902], and ruthenium tetroxide (which gives the best yields) [774, 940] (equations 324 and 325). 

The obvious hydrolysis of the nitrile must be carried out carefully to avoid racemisation.39 42 Two successful ways are direct conversion into esters 134 in acid solution or a two step process to the acids 132 via the much less easily racemised amides 133. 

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