A base-promoted cascade reaction for the regiospecificsynthesis of substituted 3-hydroxyisoindolinones under transition-metal-free conditions is developed. The base-mediated C–C bond coupling and N-α-sp3C–H bond hydroxylation are involved in this procedure, which features high regioselectivity, efficiency, and environmental friendliness. Various substituted 3-hydroxyisoindolinones, including some