A practical synthesis of 2-carboxyphenylboronic from 2-tolylboronic acid and aqueous potassium permanganate under mild conditions is reported. The title compound couples with aryl bromides containing electron-withdrawing groups to give biaryl-2-carboxylic acids.
2-carboxyphenylboronic acid - 2-tolylboronic acid - biaryl-2-carboxylic acids - Suzuki coupling - palladium catalyst