Diastereodivergent Asymmetric 1,4-Addition of Oxindoles to Nitroolefins by Using Polyfunctional Nickel-Hydrogen-Bond-Azolium Catalysts
作者:Melanie Mechler、René Peters
DOI:10.1002/anie.201502930
日期:2015.8.24
groups, and an axially chiral bisimidazolium entity participate in the stereocontrol of the direct 1,4‐addition of oxindoles to nitroolefins. Both epimers of the 1,4‐adduct are accessible in excess on demand by changes to the ligand constitution and configuration. As the products have been reported to be valuable precursors to indole alkaloids, this method should allow access to their epimeric derivatives
Squaramide-catalyzed diastereo- and enantioselective Michael addition of 3-substituted oxindoles to nitroalkenes
作者:Wen Yang、Jingsi Wang、Da-Ming Du
DOI:10.1016/j.tetasy.2012.06.018
日期:2012.7
An efficient diastereo- and enantioselectiveMichaeladdition of 3-substituted oxindoles onto nitroalkenes catalyzed by a bifunctional chiral squaramide catalyst has been developed. This organocatalytic reaction with 2 mol % of catalyst proceeded smoothly to afford 3,3-disubstituted oxindoles in high yields with good diastereoselectivities and enantioselectivities (up to 98:2 dr, 88% ee).