Bifunctional Chiral Amine Catalyzed Asymmetric Michael Reactions

In this dissertation, recent advances in the organocatalytic asymmetric Michael reactions were summarized and reviewed firstly, On this basis, The Michael reaction and it’s mechanism of aromatic ketones to nitroolefins catalyzed by chiral amine-thioureas, nitroparaffins to nitroolefins catalyzed by chiral amine-squaramide have been studied respectively.An enantioselective Michael reaction of acetophenone to substituted nitroolefins catalyzed by the chiral amine-thiourea organocatalyst and the co-catalyst4-nitrobenzoic acid with high activities and enantioselectivities(up to99%ee) was presented. The Michael reaction between aromatic ketones and nitroolefins has been investigated using density functional theory (DFT) calculation, the results state that chiral moieties of the catalyst have a great impact on yields and enantioselectivities of adducts, which is corresponded to the observed experimental results. Based on absolute configuration of the products, the ESI mass spectrometric detection of the aromatic-enamine intermediates, and the1H NMR detection of the hydrogen bonding between thiourea and nitroolefins, a plausible transition state has been proposed to explain the origin of the activation and the asymmetric induction.In the following study, an enantioselective Michael reaction of nitroparaffins with nitroolefins synergistically promoted by simple quinine-squaramide organocatalysts was presented, giving high activities and enantioselectivities for a wide range of nitroolefins and nitroparaffins(up to90:10syn/anti, up to84%ee). Furthermore, the Michael reaction between nitroparaffins and nitroolefins has been investigated using density functional theory (DFT) calculation. The calculations confirmed that quinine-squaramide catalysts are more suitable for the reaction than quinine-thiourea catalysts.