Long-chain phenols. Part 14. Synthesis of 6-n-alkylsalicylic acids and 3-n-alkylphenols

Abstract

3-Hydroxy-3-alkylphthalides obtained from phthalic anhydride and dialkylcadmium reagents have been reduced to 3-alkylphthalides and thence to 2-alkylbenzoic acids. The basic copper salts upon thermal rearrangement have yielded 6-alkylsalicylic acids and the n-undecyl, n-pentadecyl, and n-heptadecyl compounds have been shown to be identical with the hydrogenated ‘anacardic acids’ derived from several different natural products. 3-Alkylphenols were also obtained as by-products from the rearrangement, as well as from the reaction of normal copper salts. 3-Methoxyphthalic anhydride, unlike 3-nitrophthalic anhydride, gave a mixture of the two possible acyl products upon reaction with a dialkylcadmium. Hydroxylation by way of arylthallium bis(trifluoroacetates) was not successful.