the methyl and ethyl esters of 2-aroyloxyacrylic acids, 2 and 3, have been prepared. Their reactivity and selectivity have been evaluated in Diels−Alder cycloadditions with unsymmetrical dienes, which generate the corresponding adducts with high regioselectivity. No significant stereoselectivity was observed in the reaction with cyclopentadiene (9), although Lewis acid catalysis improved the exo/endo