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
Catalytic asymmetric 1,4-additions of 3-substituted oxindoles to beta-aryl, beta-heteroaryl, and beta-alkenyl nitroalkenes are described. A new homodinuclear Mn(2)(OAc)(2)-Schiff base 1 complex was required to realize high diastereo- and enantioselectivity. Mn(2)(OAc)(2)-1 (1-5 mol %) promoted the 1,4-additions in 99-83% yield, 96-85% ee, and >30:1-5:1 dr at room temperature, providing useful chiral
描述了催化不对称 1,4-加成 3-取代 oxindoles 到 β-芳基、β-杂芳基和 β-烯基硝基烯烃。需要一种新的同双核 Mn(2)(OAc)(2)-Schiff base 1 复合物来实现高非对映选择性和对映选择性。Mn(2)(OAc)(2)-1 (1-5 mol %) 以 99-83% 的产率、96-85% 的 ee 和 >30:1-5:1 dr 促进 1,4-加成室温下,为合成具有邻位季/叔碳立体中心的 β-氨基羟吲哚提供有用的手性构件。
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).
A simple alkylthiourea was found to be an effective catalyst for the Michaeladditionreaction of 3-substitutedoxindole to nitroolefins. A number of 3,3′-substituted oxindole derivatives, which have two vicinal quaternary-tertiary chiral centers were synthesized with up to 99% yield, 19:1 dr and 98% ee.
Asymmetric Michael Addition of
<i>N</i>
‐Boc‐Protected Oxindoles to Nitroalkenes Catalyzed by a Chiral Secondary Amine
作者:Chuan Wang、Xuena Yang、Dieter Enders
DOI:10.1002/chem.201200079
日期:2012.4.16
New mission for prolinol ethers: A secondary‐amine‐catalyzedMichaeladdition of N‐Boc‐protectedoxindoles to nitroalkenes through a Brønsted base activation mode has been developed, furnishing the products in excellent yields (88–98 %), diastereoselectivities (d.r.=98:2–>99:1) and high to excellent enantioselectivities (82–>99 % ee; see scheme).