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Updated: Jul 17, 2025

Preparation of N-2-alkoxyvinylsulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines
Published on: January 3, 2018
Synthesis of Neocaesalpin A, AA, and Nominal Neocaesalpin K
Sven M Papidocha1, Hendrik H Bulthaupt1, Erick M Carreira1
1Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, 8093, Zürich, Switzerland.
Abstract:
The first total synthesis of heavily oxidized cassane-type diterpenoid neocaesalpin A (1) is disclosed. At the heart of the synthesis lies an intermolecular Diels-Alder reaction that rapidly assembles the target framework from commercial materials. A carefully orchestrated sequence of oxidations secured the desired oxygenation pattern. Late-stage release of the characteristic butenolide occurred through a novel mercury(II)-mediated furan oxidation. Successful extension of the route allowed preparation of neocaesalpin AA (2) as well as nominal neocaesalpin K (3) and suggested structural revision of neocaesalpin K, leading to the hypothesis that the two are likely the same natural product with correct assignment as 2.
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