A facile method employing styrene-type carboxylic esters or amides in the presence of PhICl2 in CH3CN was developed to achieve the synthesis of 6-endo products 3,4-dihydroisocoumarins or 3,4-dihydroisocoumarin-1-imines in good to high yields. This metal-free regioselective intramolecular chlorolactonization process was proposed to involve a PhICl2-mediated oxidative C-O bond formation followed by C-Cl bond formation.