Asymmetric Mannich Reaction under Wet Conditions

Significance

A first three-component Mannich reaction in the presence of water without using any organic solvents is reported. The reaction is catalyzed by a silyloxyprolinetetrazole catalyst. Several cyclic ketones and 3-pentanone were converted into the Mannich adduct with high syn-diastereoselectivity and enantioselectivity when dimethoxyacetaldehyde was used as the aldehyde component. α-Imino ethyl glyoxylate was also applied in a two-component Mannich reaction, albeit under different conditions. When silyl­oxyproline was used as catalyst in aqueous NaHCO₃, products were obtained in moderate to good yields with excellent diastereoselectivities and enantioselectivities.