Organocatalyzed Asymmetric Michael Addition of 4‐Monosubstituted‐pyrazol‐5‐ones to Enones: Construction of Vicinal Quaternary and Tertiary Stereocenters

Pyrazolone moiety bearing an all‐carbon quaternary stereogenic center is frequent in biologically active products and pharmaceuticals. The catalytic route for the construction of quaternary carbon centers poses a formidable challenge . In this report, catalytic asymmetric Michael addition of 4‐monos...

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Bibliographic Details
Published in:European journal of organic chemistry 2024-04, Vol.27 (15), p.n/a
Main Authors: Goyal, Pooja, Dubey, Akhil K., Chowdhury, Raghunath
Format: Article
Language:English
Subjects:
Asymmetric Organocatlysis
Asymmetry
Carbon
Enantiomers
Enones
Iminium catalysis
Pyrazolones
Quaternary stereocenter
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Summary:Pyrazolone moiety bearing an all‐carbon quaternary stereogenic center is frequent in biologically active products and pharmaceuticals. The catalytic route for the construction of quaternary carbon centers poses a formidable challenge . In this report, catalytic asymmetric Michael addition of 4‐monosubstituted‐pyrazol‐5‐ones to simple enones catalyzed by primary amine‐Brønsted acid composite has been developed. An array of pyrazolone derivatives bearing vicinal all carbon quaternary and tertiary stereocenters, were obtained in moderate to good diastereoselectivities (up to 92 : 8 dr) and good to excellent enantiomeric excess (up to 99 % ee). In addition, antipode for enantiomers of the pyrazolone derivatives were also realized in good to high stereoselectivities (up to 92 : 8 dr and up to 98 % ee). Asymmetric Michael addition of 4‐monosubstituted‐pyrazol‐5‐ones to simple enones is realized on capitalization of iminium activation mode of organocatalyst. The pyrazolone derivatives featuring vicinal all carbon quaternary and tertiary stereocenters, were obtained in good to excellent stereoselectivities.
ISSN:1434-193X
1099-0690
DOI:10.1002/ejoc.202400002