Palladium-Catalyzed Cyclocarbonylation of 3-(Heteroaryl)allyl Acetates1

Article abstract of DOI:10.1021/jo00005a046

Acetoxybenzofurans, acetoxybenzothiophenes, acetoxyindoles, and acetoxycarbazoles were obtained in high yields by cyclocarbonylation of 3-furyl-, 3-thienyl-, 3-pyrrolyl-, and 3-indolylallyl acetates, respectively, in the presence of Ac2O, NEt3, and a catalytic amount of PdCl2(PPh3)2 at 130 - 170 deg C under 50 - 70 atm of CO. 3-(3-Furyl)allyl and 3-(3-thienyl)allyl acetates cyclized selectively at the 2-position of the heterocyclic nucleus to give 7-acetoxybenzofuran and 7-acetoxybenzothiophene, respectively.The synthetic utility of the reaction was demonstrated by the synthesis of canabifuran from isothymol.