Synthesis of Lactams by Isomerization of Oxindoles Substituted at C-3 by an ω-Amino Chain
摘要:
Oxindoles substituted at N-1 by electron-withdrawing groups and at C-3 by omega-amino chains of various lengths undergo mild and easy isomerization to new 5- to 12-membered lactams in good yields (3096%). As efficient asymmetric syntheses of diversely 3,3-disubstituted oxindoles are currently developed, this isomerization provides a new and valuable access to medium-sized lactams alpha-substituted with a quaternary asymmetric carbon bearing a 2-aminophenyl residue.
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).
Chiral Bifunctional Thiosquaramides as Organocatalysts in the Synthesis of Enantioenriched 3,3-Disubstituted Oxindoles
作者:Patricia Rodríguez-Ferrer、Daniel Naharro、Alicia Maestro、José M. Andrés、Rafael Pedrosa
DOI:10.1002/ejoc.201901327
日期:2019.10.17
Four novel chiral bifunctional thiosquaramides have been prepared from cyclopentyl dithiosquarates and diamines derived from natural l‐valine and l‐tert‐leucine. The novel thiosquaramides have been tested as organocatalyst in the nitro‐Michaeladdition of 3‐substituted oxindoles to different β‐aryl‐substituted nitroalkenes. The reaction occurred easily in high yields and excellent stereoselectivities
phase‐transfer reaction system can be applied to highly enantioselectiveconjugateaddition and aldol reactions under the influence of chiral bifunctional ammonium bromides as key catalysts. The structure of the chiral ammonium enolate intermediate is discussed based on the single‐crystal X‐ray structures of relevant ammonium salts and the importance of bifunctional design of catalyst is clearly explained in the