Electrochemical Access to N-Aryliminium Ion Electrophiles from N-Aryl Amino Acids

N-aryl hemiaminals are versatile synthetic intermediates that can serve as placeholders for N-aryliminium ions. We report the non-Kolbe anodic decarboxylation of N-arylamino acids for efficient synthesis of an array of N-aryl hemiaminals. The reported electrochemical method is convenient and air-tolerant with a simple workup, user-friendly controls, and employs inexpensive electrode materials. We demonstrate the utility of these intermediates in traditional Povarov cyclizations under the action of Lewis acid affording 4-phenyltetrahydroquinolines (up to 70% yield over two steps). We also demonstrate the direct electrochemical synthesis of polycyclic frameworks relevant to several bioactive natural products from simple N-arylamino acid starting materials.