Palladium-catalyzed intramolecular cyclization of o-ethynylbenzoic acids and o-ethynylbenzamides:: Preparation of isocoumarins and isoquinolin-1-ones

Treatment of the o-ethynylbenzoic acids 1A with a catalytic amount of Pd(II) and triethylamine resulted in the 6-endo-dig cyclization to give the 3-substituted isocoumarins 3 as major products in moderate to good yields. Similarly, the palladium-catalyzed cyclization of o-ethynylbenzamides 1B also proceeded but afforded only the isoquinolin-1-ones 3B.