Highly Diastereo- and Enantioselective Synthesis of Isoxazolone-Spirooxindoles via Squaramide-Catalyzed Cascade Michael/Michael Addition Reactions

A highly enantioselective [3+2] annulation of 3-((2-oxoindolin-3-yl)­oxy)­acrylates with isoxazol-5­(4H)-ones has been accomplished by squaramide-catalyzed cascade Michael/Michael addition reactions under mild conditions. The corresponding isoxazolone-spirooxindoles with four continuous stereocenter...

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Published inJournal of organic chemistry Vol. 85; no. 23; pp. 15325 - 15336
Main Authors Wang, Yu, Du, Da-Ming
Format Journal Article
LanguageEnglish
Published WASHINGTON American Chemical Society 04.12.2020
Amer Chemical Soc
Subjects
acrylates
ammonium chloride
chemical reactions
Chemistry
Chemistry, Organic
enantioselective synthesis
enantioselectivity
organic chemistry
Physical Sciences
Science & Technology
ORGANOCATALYSTS
ACID
CITRINADIN-A
MICHAEL-ADDITION
ONE-POT
3-HYDROXYOXINDOLES
BISPIROOXINDOLES
3-AMINO
DERIVATIVES
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Summary:A highly enantioselective [3+2] annulation of 3-((2-oxoindolin-3-yl)­oxy)­acrylates with isoxazol-5­(4H)-ones has been accomplished by squaramide-catalyzed cascade Michael/Michael addition reactions under mild conditions. The corresponding isoxazolone-spirooxindoles with four continuous stereocenters were obtained in moderate to high yields with excellent stereoselectivities (up to >20:1 dr, 97% ee). The synthetic practicality of this methodology was illustrated by performing the reaction on a gram scale with the same efficiency and stereoselectivity. Meanwhile, the isoxazol-5­(4H)-one ring could be opened by the reaction with iron powder and ammonium chloride, and the corresponding acyl derivative can be obtained with a maintained yield and stereoselectivity.
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content type line 23
ISSN:0022-3263
1520-6904
1520-6904
DOI:10.1021/acs.joc.0c02150