4-Methoxybenzyl esters

Dimethoxybenzyl esters prepared from the acid chloride and the benzyl alcohol are readily cleaved oxidatively by DDQ (CH2CI2, H2O, rt, 18 h, 90-95% yield). A 4-methoxybenzyl ester was found not to be cleaved by DDQ. The authors have also explored the oxidative cleavage (ceric ammonium nitrate, CH3CN, H2O, 0°, 4 h, 65-97% yield) of a variety of 4-hydroxy- and 4-amino-substituted phenolic esters. ... 

Protection of carboxylic acids 2,6-Dimethoxybenzyl esters on treatment with DDQ (1 equiv.) at 25° in CH2C12 containing some water are slowly converted into the corresponding acids in 90-95% yield. 4-Methoxybenzyl esters are stable to this oxidation, whereas 2,4,6-trimethoxybenzyl esters are hydrolyzed in the presence of silica gel. 

Substituted o-benzenesulfonamide 61 was found to be a good source for the synthesis of 4-methoxybenzyl esters by the reaction with alcohols and phenols in the presence of sodium hydride at room temperature <1998TL1799>. Treatment of cyclic sulfonamide 61 with aqueous KOH in dimethylformamide (DMF) yielded 4-methoxybenzyl alcohol together with benzenesulfonamide 53 (Scheme 5). 

Methylenedioxy)benzyl esters (piperonyl esters) are cleaved more readily than the 4-methoxybenzyl ester by acid hydrolysis with 2 M HBr/AcOH or TFA at room temperature within 5 minutes.3,4-(Methylenedioxy)benzyl esters are readily prepared either by transesterification of anoino acid 4-nitrophenyl esters with 3,4-(methylenedioxy)benzyl alcohol in imidazole/dioxane (rt, 12 h) or from Nps-protected amino acids with 3,4-(methyl-enedioxy)benzyl chloride/TEA in DMF at room temperature. 

The 4-methoxybenzyl esters are prepared by transesterification of N-protected amino acid nitrophenyl esters with 4-methoxybenzyl alcohol in the presence of several equivalents of imidazole, followed by subsequent acidolytic cleavage of the N-protecting group.Alternatively, reaction of N-protected amino acids silver(I) salts with 4-methoxybenzyl halides (TEA/CHCI3, rt, 24 h, 60% yield) or treatment of N-protected amino acids with 4-meth-... 

Weygand and Hunger introduced the 4-methoxybenzyl ester and showed that this group can be cleaved with TFA at For the preparation of these esters, various methods have... 

Benzylic oxidation of alkoxybenzyl ethers is particularly facile, and since some of the more activated derivatives are cleaved under conditions which leave benzyl, various ester, and formyl groups unaffected, they have found application in the protection of primary and secondary alcohols. Deprotection with DDQ in dichloromethane/water follows the order 3,4-dimethoxy > 4-methoxy > 3,5-dimethoxy > benzyl and secondary > primary, thus allowing the selective removal of one function in the presence of another. 2,6-Dimethoxybenzyl esters are readily cleaved to the corresponding acids on treatment with DDQ in wet dichloromethane at rt, whereas 4-methoxybenzyl esters are stable under these conditions. Oxidative cleavage of N-linked 3,4-dimethoxybenzyl derivatives with DDQ has also been demonstrated. ... 

Acetic acid 4-methoxybenzyl ester. See p-Anisyl acetate... 

Synonyms p-Anisyl formate Formic acid 4-methoxybenzyl ester 4-Methoxybenzenemethanol methanoate 4-Methoxybenzyl formate p-Methoxybenzyl formate... 

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