Efficient synthesis of 3-acyl-5-hydroxybenzofurans via copper(II) triflate-catalyzed cycloaddition of unactivated 1,4-benzoquinones with 1,3-dicarbonyl compounds

A method to prepare a variety of substituted 3-acyl-5-hydroxybenzofurans efficiently that relies on copper(II) triflate-catalyzed cycloaddition of unactivated 1,4-benzoquinones with 1,3-dicarbonyl compounds is reported. The reaction was shown to be operationally straightforward and proceeds expediently under mild conditions to give the corresponding products in good to excellent yields (up to 95%) and with complete regioselectivity.