Irradiation of aryl esters of N-hydroxyphthalimides in the presence of unactivated olefins promotes a mild and regioselective hydroesterification. Optimal results are obtained with the aid of fac-Ir(dFppy) 3 in CH 2 Cl 2 . Terminal and 1,1-disubstituted olefins provide primary esters, and trisubstituted olefins provide secondary esters. The anti-Markovnikov selectivity is consistent with alkyl radical intermediates, which are also indicated by the formation of cyclized products from dienes. Monoacylated diols are formed from trisubstituted and tetrasubstituted olefins in the presence of water.