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

摘要

Synthetic approaches to the furanocembrane family of natural products, e. g. lophotoxins, pukalides, bipinnatins, based on: i) an intramolecular cyclisation of an alpha,beta-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.