화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.137, No.36, 11582-11585, 2015
Asymmetric Anion-pi Catalysis: Enamine Addition to Nitroolefins on pi-Acidic Surfaces
Here we provide experimental evidence for anion-pi catalysis of enamine chemistry and for asymmetric anion-pi catalysis. A proline for enamine formation on one side and a glutamic acid for nitronate protonation on the other side are placed to make the enamine addition to nitroolefms occur on the aromatic surface of pi-acidic naphthalenediirnides. With increasing pi acidity of the formally trifunctional catalysts, rate and enantioselectivity of the reaction increase. Mismatched and more flexible controls reveal that the importance of rigidified, precisely sculpted architectures increases with increasing pi acidity as well. The absolute configuration of stereogenic sulfoxide acceptors at the edge of the pi-acidic surface has a profound influence on asymmetric anion-pi catalysis and, if perfectly matched, affords the highest enantio- and diastereoselectivity.