HBF4-catalyzed Mannich-type reaction of silyl enolates with aldimines took place smoothly in aq. org. solvent to afford beta-aminocarbonyl compds. in high yields. The HBF4-catalyzed Mannich-type reaction also proceeded smoothly in water without org. solvent in the presence of a surfactant. A three-component synthesis starting from aldehyde, amine, and silyl enolate was successfully realized by means of a Bronsted acid in aq. media. [on SciFinder (R)]