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Updated: Jul 10, 2026

Preparation of N-(2-alkoxyvinyl)sulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines
Published on: January 3, 2018
Toward the Synthesis of Pestalustaine A: Structural Revision and Formation of Original Strained Tricyclic
Wei Cao1,2, Alicia Ross3, Jean-Pierre Baltaze1
1Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Orsay, France.
Abstract:
We report our quest toward the total synthesis of the reported structure of the sesquiterpene pestalustaine A and its unprecedented tricyclic skeleton. Our retrosynthesis involved a transannular Michael addition of a 1,3-keto-ester and enal-containing bicyclo[4.4.1]undec-3-ene obtained from the ring expansion of a chiral γ,γ-disubstituted cyclohexanone and stereoselective Hosomi-Sakurai reaction. Serendipity allowed us to uncover powerful divergent and unexpected cyclizations of this bicycle in ionic or oxidative conditions, giving access to complex tricyclic architectures such as tricyclo[5.2.1.12,5]undecane, octahydro-1,5-methanonaphthalene, octahydro-12,6-methanonaphthalene frameworks, and the octahydro-1,5-methanoazulene reported skeleton of pestalustaine A. The present synthetic study also led us to note a discrepancy between the reported structure of pestalustaine A and the 2D NMR data, which led us to propose a revised structure of the natural product to a caryophyllene-type framework, a reassignment supported by computational prediction of NMR chemical shifts.
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