An iridium-catalyzed asymmetric allylation of dioxindoles, 3-hydroxyoxindoles, regulated by prosthetic groups has been accomplished under mild conditions. The methodology is applicable to a diverse array of 3-hydroxyoxindole and cinnamyl acetate substrates. A range of 3-ally'-3-hydroxyoxindoles containing vicinal tetrasubstituted and trisubstituted stereocenters can be efficiently synthesized in one-step with excellent enantioselectivity (up to >99% enaniomeric excess (ee)) and good diastereoselectivity (up to 11:1 diastereomeric ratio (dr)).