Related Experiment Video
Updated: Mar 3, 2026

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
An Unexpected Isomerization for the Total Synthesis of Daphnepapytone A
1Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104 Freiburg i. Bg., Germany.
None:
We report a high-yielding total synthesis of sesquiterpenoid daphnepapytone A from (S)-glycidol. The groundwork for the synthesis is laid via reductive cleavage of a bicyclic Pauson-Khand-derived cyclopentenone ether, giving efficient access to a trisubstituted chiral cyclopentenone which is difficult to obtain by other means. To introduce the cyclobutane motif, the enone was irradiated in the presence of allene gas, yielding the unwanted exo-cyclobutane at worst and 1:1 mixtures of the endo- and exo-product at best. A serendipitous epimerization of an aldehyde in the following steps converted the unwanted exo-epimer into the endoenantiomer, which significantly improved the final yield. The final cage was connected with a second Pauson-Khand reaction, requiring only one more step to yield the natural product.
More Related Videos
11:04Preparation of Enantiopure Non-Activated Aziridines and Synthesis of Biemamide B, D, and epiallo-Isomuscarine
Published on: June 13, 2022
14:11Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Related Concept Videos
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
SN2 Reaction: Stereochemistry
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
SN1 Reaction: Stereochemistry
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...