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Updated: Aug 13, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
An expeditious stereoselective synthesis of natural (-)-Cassine via cascade HWE [3 + 2]-cycloaddition process
Claus Herdeis1, Patrick Küpper, Sophie Plé
1Institut für Pharmazie und Lebensmittelchemie der Universität Würzburg, Am Hubland, 97074, Würzburg, Germany. herdeis@pharmazie.uni-wuerzburg.de
Abstract:
l-Rhamnose is transformed to (-)-Cassine via a remarkable four step one pot reaction. The Horner-Wadsworth-Emmons [3 + 2]-1,3-dipolar cycloaddition reaction cascade is the pivotal step in this reaction sequence and makes the synthesis highly efficient.
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If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.

