A novel palladium-catalyzed aminomethylamination of aminoalkenes with an aminal, functioning not only as an aminomethylation reagent but also as an oxidant, was developed. This direct and operationally simple protocol provides a fundamentally novel and unique approach toward the synthesis of 2-(2-aminoethyl)indoles and 2-(2-aminoethyl)pyrrolidines, which are important building blocks in synthetic organic chemistry. The unity of this method was highlighted by the rapid synthesis of Alosetron, a drug used for the treatment of irritable bowel syndrome.