The highly enantioselective Michael addition of ketones to nitrodienes catalyzed by the efficient organocatalyst system of pyrrolidinyl-thioimidazole and chiral thioureido acid
The highlyenantioselectiveMichaeladdition reaction of ketones to nitrodienes was promoted efficiently by the accessible and fine-tunable organocatalytic system of pyrrolidinyl-thioimidazole and chiral thioureido acid. The corresponding adducts were afforded in good yields with high diastereoselectivities (up to 99 : 1) and excellent enantioselectivities (up to 99% ee).
Ion-Supported Chiral Pyrrolidines as Enantioselective Catalysts for Direct Michael Addition of Nitroalkenes in [BMIm]PF<sub>6</sub>
作者:Zhenyuan Xu、Danqian Xu、Shuping Luo、Huadong Yue、Liping Wang、Yunkui Liu
DOI:10.1055/s-2006-950443
日期:2006.9
Imidazolium-supported-pyrrolidine-catalyzed asymmetric Michaeladdition reactions of unmodified ketones and aldehydes to nitroalkenes were performed in [BMIm]PF 6 to give products in up to 98% yield and 99% enantioselectivity. The catalytic system presented a synergistic effect in the improvement of reaction performance and could be recycled.
A novel and effective organocatalytic system consisting of pyrrolidinyl-thioimidazole and a chiral thioureido acid efficiently catalyzed the asymmetric Michaeladdition reactions of ketones to nitroolefins to afford the adducts with high diastereoselectivities (up to 99 : 1) and excellent enantioselectivities (up to 99% ee).
Chiral N-Heterocyclic Carbene Ligands Bearing a Pyridine Moiety for the Copper-Catalyzed Alkylation of<i>N</i>-Sulfonylimines with Dialkylzinc Reagents
Amino acid‐derived chiral imidazolium salts, each bearing a pyridine ring, were developed as N‐heterocyclic carbeneligands. The copper‐catalyzed asymmetric alkylation of various N‐sulfonylimines with dialkylzincreagents in the presence of these chiral imidazolium salts afforded the corresponding alkylated products with high enantioselectivity (up to 99 % ee). The addition of HMPA to the reaction
Asymmetric Michaeladditionreactions of unmodified ketones to nitroalkenes were performed in PEGs catalyzed by novel pyrrolidinyl-thioimidazolium salts to give products in up to 97% yield and 99% enantioselectivity; ESI mass spectrometric detection for the first time gave evidence of the presence of the PEG-organocatalyst host-guest complex.