GB846737A - 3-substituted 4-hydroxybenzoic acids and their preparation - Google Patents

Abstract

The invention comprises 3-(g ,g -dimethylallyl)-4.hydroxy-benzoic acid, 3-isoamyl-4-hydroxy benzoic acid and their esters and alkali metal salts. They may be prepared by reacting an alkali metal salt of a p-hydroxy benzoic acid ester with a g ,g -dimethyl-alkyl halide under essentially anhydrous conditions in an inert solvent to produce the corresponding ester of 3-(g ,g -dimethyl-allyl)-4-hydroxy-benzoic acid. This ester may be treated with alkali to give the corresponding alkali metal salt of the hydroxy acid, which may be isolated, by conventional means, if desired, or acidified to give the free hydroxy acid. The side chain may then be hydrogenated catalytically to give the corresponding isoamyl compound. Alternatively the side chain may be hydrogenated first and the resulting 3-isoamyl-4-hydroxy benzoate converted to the free acid. In examples ethyl p-hydroxy benzoate is treated with sodium in toluene and g ,g -dimethyl-allyl bromide added to the mixture. The resulting ester is then saponified and reduced or reduced and then saponified. These compounds are stated to be useful as precursors in the production of novobiocin and a further example describes the addition of 3-isoamyl- and 3-(g ,g -dimethylallyl)-4 hydroxy benzoic acid to fermentation broths containing a culture of Streptomyces Spheroides and a nutrient medium.