Benzoic acids, aryl esters hydrolysis

Esters have been prepared in 63-73% yields from several simple cycloalkyl and aryl alkyl ketones by reaction at room temperature with per-benzoic acid. The larger radical of the ketone appears as the alcohol fragment of the ester. Cyclic ketones are oxidized by potassium persulfate and sulfuric acid to esters from which o>-hydroxy aliphatic esters are obtained upon hydrolysis and reesterification. Peracetic acid in acetic anhydride converts salicylaldehyde to o-hydroxyphenyl formate (88%). ... 

The procedure has also been applied to halobenzoic acids.3 Thus p-bromo-benzoic acid (6) was converted into the corresponding 2-oxazoline (7) as usual, and then into the Grignard derivative (8). This is, in effect, an aryl Grignard reagent with a protected carboxyl function. Reaction with an electrophile, for example benzonitrile, gives (9). The final step is hydrolysis. If carried out in 5-7% ethanolic sulfuric acid, the ester (10b) is obtained if carried out in an aqueous medium, the free acid (10a) is obtained. 

As outlined in Scheme 6, isovanillin (35) was converted to aryl iodide 36 via MOM-protection, protection of the aldehyde, and subsequent iodination. Hydrolysis of the acetal and Wittig olefination delivered phenol 37 after exposure of the intermediate aldehyde to methanolic hydrochloric acid. Epoxide 41, the coupling partner of phenol 37 in the key Tsuji-Trost-reaction, was synthesized from benzoic acid following a procedure developed by Fukuyama for the synthesis of strychnine [62]. Birch reduction of benzoic acid with subsequent isomerization of one double bond into conjugation was followed by esterification and bromohydrin formation (40). The ester was reduced and the bromohydrin was treated with base to provide the epoxide. Silylation concluded the preparation of epoxide 41, the coupling partner for iodide 37, and both fragments were reacted in the presence of palladium to attain iodide 38. 

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