Spirobicyclic and Tetracyclic Pyrazolidinones: Syntheses and Properties

The stereoselective syntheses of spirobicyclic and tetracyclic pyrazolidinones are reported based on a (3+2) annulation between hydrazones and α‐oxoketenes. Some of these conformationally constrained molecules were resolved as enantiopure materials by HPLC techniques and evaluated as aminocatalysts...

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Published inEuropean journal of organic chemistry Vol. 2019; no. 35; pp. 6034 - 6043
Main Authors Perez, Fabien, Leveille, Thibault, Bertolotti, Mathilde, Rodriguez, Jean, Coquerel, Yoann
Format Journal Article
LanguageEnglish
Published WEINHEIM Wiley 22.09.2019
Wiley Subscription Services, Inc
Wiley-VCH Verlag
Subjects
Chemical reactions
Chemical Sciences
Chemistry
Chemistry, Organic
Cycloaddition
C‐H activation
Diastereoselectivity
Hydrazones
Organic chemistry
Organocatalysis
Physical Sciences
Science & Technology
Spiro compounds
Stereoselectivity
Synthetic methods
MICHAEL REACTION
C-H activation
ORGANOCATALYSTS
Synthetic methods
SILYL ETHERS
Organocatalysis
Diastereoselectivity
Spiro compounds
CATALYSTS
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Summary:The stereoselective syntheses of spirobicyclic and tetracyclic pyrazolidinones are reported based on a (3+2) annulation between hydrazones and α‐oxoketenes. Some of these conformationally constrained molecules were resolved as enantiopure materials by HPLC techniques and evaluated as aminocatalysts for iminium activation in a model Diels–Alder cycloaddition. Spirobicyclic and tetracyclic pyrazolidinones are prepared by a (3+2) annulation between in situ generated hydrazones and α‐oxoketenes. Notably, palladium‐catalyzed cyclizations led to tetracyclic backbones through aromatic C–H bond activation. Some of these molecules were evaluated as organocatalysts for the iminium activation of enals in a model Diels–Alder cycloaddition.
ISSN:1434-193X
1099-0690
DOI:10.1002/ejoc.201900989