Mechanism: Addition of formaldehyde to the starting amine gives an iminium ion which reacts in a sigmatropic reaction to another rearranged iminium ion (but stabilized by the phenyl group). Hydrolysis splits of the benzaldehyde unit and the final step is methylation. This rearrangement reaction generally takes place at lower temperatures then the Cope reaction but still high. Catalysis is possible with Lewis acid (BF3, ZnCl2) and protic acid (HCl).
Also known as: Aza-Cope Mannich reaction, cationic aza-Cope reaction, 2-azonia-3,3-sigmatropic rearrangement Put to use in: Total synthesis of (-)-strychnine by the Overman group in 1993 (Knight et al. DOI) Enantioselective: an asymmetric aza-Cope was recently accomplished using a chiral phosphoric acid (Rueping et al. 2008DOI):
Examples from recent literature: An N-amino-3-aza Cope (Glória et al. 2008DOI):