A HOAc‐catalyzed aryloxy/alkoxy‐assisted nucleophilic addition of 2‐methylquinolines to aldehydes in water has been described. The reaction provides an efficient and direct access to hydroxyquinolines in moderate to good yields. In addition, a HOAc/1,3‐DMBBA (1,3‐dimethylbarbituric acid) synergistic organocatalysis system were also developed for the synthesis of alkenylquinolines.