New synthesis of 4-methoxyisophthalic acid

A new synthetic route to 4-methoxyisophthalic acid, the key intermediate in the synthesis of Picotamide, is reported. The new protocol starts from commercially available and cheap 4-methylphenol and includes four steps: esterification, Fries rearrangement, methylation, and oxidation; the overall yield is 49%. Unlike the traditional Blanc chloromethylation/oxidation scheme, the proposed procedure avoids using volatile and corrosive hydrochloric acid.