SYNTHESIS OF ISOCOUMARINS: RHENIUM COMPLEX-CATALYZED CYCLIZATION OF 2-ETHYNYLBENZOIC ACIDS

When 2-ethynylbenzoic acids were treated with a catalytic amount of a rhenium complex, such as ReCl(CO())5, 6-endo cyclization of 2-ethynylbenzoic acids proceeded with a high selectivity to give the corresponding isocoumarins in moderate to good yields.