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Asymmetric Mannich Reaction under Wet Conditions
Y. Hayashi*, T. Urushima, S. Aratake, T. Okano, K. Obi
Tokyo University of Science, Japan
23 January 2008 (online)
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.