Self-Assembled Organocatalysts

Significance

The use of self-assembled organocatalysts composed of α-amino acids and alkaloids in the direct asymmetric Michael addition of ketones and aldehydes to aromatic nitroolefins is reported. Ionic interactions between the ammonium and the carboxylate cause the two modules to self-assemble (see general concept). l-Phenylglycine together with quinidine derivative 2 carrying a thiourea moiety afforded the highest asymmetric induction. The assembly of l -proline and 2 was in certain cases less enantioselective, but more active. The authors observed strong matching and mismatching effects between the two catalyst modules.

Review: S. B. Tsogoeva Eur. J. Org. Chem. 2007, 1701-1716.