Asymmetric synthesis of pyrano[2,3-c]pyrazoles via a cascade reaction between Morita–Baylis–Hillman acetates of nitroalkenes and pyrazolones

The first organocatalytic enantioselective cascade reaction of Morita–Baylis–Hillman acetates of nitroalkenes with pyrazolones has been developed. With 20 mol% of chiral tertiary-amine squaramide, 1,4,5,6-tetrahydropyrano[2,3-c]pyrazoles were afforded in moderate yields (up to 71%) with excellent st...

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Bibliographic Details
Published in:Tetrahedron 2016-07, Vol.72 (27-28), p.4047-4054
Main Authors: Xie, Jin, Sha, Feng, Wu, Xin-Yan
Format: Article
Language:English
Subjects:
Acetates
Asymmetry
Cascade chemical reactions
Cascade reaction
Enantioselective organocatalysis
MBH acetates
Pyrano[2,3-c]pyrazoles
Pyrazolones
Squaramide
Stereoselectivity
Synthesis (chemistry)
Tetrahedrons
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Summary:The first organocatalytic enantioselective cascade reaction of Morita–Baylis–Hillman acetates of nitroalkenes with pyrazolones has been developed. With 20 mol% of chiral tertiary-amine squaramide, 1,4,5,6-tetrahydropyrano[2,3-c]pyrazoles were afforded in moderate yields (up to 71%) with excellent stereoselectivities (up to>99:1 dr and up to 98% ee). [Display omitted]
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2016.05.033