Synthetic studies towards furanocembrane diterpenes. A total synthesis of bis-deoxylophotoxin

Abstract

Synthetic approaches to the furanocembrane family of natural products, e.g. lophotoxins, pukalides, bipinnatins, based on: i) an intramolecular cyclisation of an α,β-unsaturated acyl radical intermediate into a conjugated enone, viz.18 → 17, and ii) an intramolecular Stille coupling reaction involving a 2-stannylfuran and a vinyl iodide, i.e.67 → 68, are described. A total synthesis of bis-deoxylophotoxin 71a, the probable biological precursor to the neurotoxin lophotoxin 1, isolated from species of the Pacific sea whip Lophogorgia, is then presented.