Organocatalysis with proline derivatives: improved catalysts for the asymmetric Mannich, nitro-Michael and aldol reactions
作者:Alexander J. A. Cobb、David M. Shaw、Deborah A. Longbottom、Johan B. Gold、Steven V. Ley
DOI:10.1039/b414742a
日期:——
Tetrazole and acylsulfonamide organocatalysts derived from proline have been synthesised and applied to the asymmetric Mannich, nitro-Michael and aldol reactions to give results that are superior to the proline-catalysed counterpart.
Novelbifunctionalchiralsquaramide–amine organocatalysts have been developed by rational combination of pyrrolidine and a cinchona alkaloid. The catalysts promoted the enantioselective Michael addition of both mono- and diketones to a broad range of nitroalkenes providing the corresponding products in moderate to high yields with excellent enantioselectivities and diastereoselectivities (up to 96%
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 Homo-Proline Tetrazole as an Improved Organocatalyst for the Asymmetric Michael Addition of Carbonyl Compounds to Nitro-Olefins
作者:Steven V. Ley、Claire E. Mitchell、Alexander J. Cobb
DOI:10.1055/s-2005-862392
日期:——
A new homo-proline tetrazole derivative 7 has been prepared and shown to have improved properties for achieving asymmetric Michaeladdition of carbonyl compounds to nitro-olefins.
benzenesulfonic acid (DBSA) leads to highly effective and selective organocatalysts in water. The in situ generated catalysts catalyze highly stereoselective desymmetrization of prochiral ketones via directaldol reactions (up to >16:1 dr, >99% ee) in water using micelle as reaction media. The current strategy was also applied in asymmetric Michael addition leading to a catalytic system with good activity