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Updated: Jun 19, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Total synthesis of (+)-intricarene using a biogenetically patterned pathway from (-)-bipinnatin J, involving a novel
Bencan Tang1, Christopher D Bray, Gerald Pattenden
1School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Abstract:
An asymmetric synthesis of the furanobutenolide-based macrocyclic diterpene (-)-bipinnatin J (4a) isolated from the gorgonian octocoral Pseudopterogorgonia bipinnata is described. The synthesis is based on elaboration of the chiral lactone-substituted vinyl iodide 26b from (+)-glycidol, followed by an intermolecular Stille coupling reaction with the stannylfurfural 27, leading to 28a, and then an intramolecular Nozaki-Hiyama-Kishi allylation reaction, 28b --> 4a. Treatment of (-)-bipinnatin J (4a) with VO(acac)2-tBuO2H followed by acetylation of the tautomeric hydroxypyranone product 7/8, next gave the acetoxypyrone 30. When the acetoxypyranone 30 was heated in acetonitrile in the presence of DBU, it gave (+)-intricarene 1, which is found in P. kallos, via a novel transannular [5+2] (or 1,3-dipolar) cycloaddition involving the butenolide-oxidopyrylium ion intermediate 31. We believe that this total synthesis of (+)-intricarene 1 mimics its most likely origin in nature via oxidation of (-)-bipinnatin J (4a), presumably involving photochemically generated singlet oxygen or possibly a P450 monooxygenase enzyme system.
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