Mannich-type reaction of N,O-acetals with ketones mediated by a combination of TiCl4 and PhSiCl3

A combination of TiCl 4 and PhSiCl 3 efficiently conducts the Mannich-type reaction of N,O-acetals with ketones to afford α-substituted cyclic amine derivatives in good yields. This method was applicable to preparation of azabicyclo compounds by the intramolecular Mannich-type reaction.