Total Synthesis of (±)Variotin and Its Analogs

Abstract 1-Sorboyl-2-pyrrolidone was prepared from sorbic acid and 2-ethoxy-1-pyrroline using 1-methyl-2-chloropyridinium iodide as a coupling reagent. Variotin and its analogs were similarly synthesized from lactim ethers and (2E,4E,6E)-8-hydroxy-2,4,6-dodecatrienoic acids without protecting the hydroxyl group at C-8. (2E,4E,6E)-8-Hydroxy-6-methyl-2,4,6-dodecatrienal, a precursor of trienoic acid, was synthesized by the elimination of methanol from (2E,6E)-8-acetoxy-5-methoxy-6-methyl-2,6-dodecadienal prepared from the reaction of 1-trimethylsiloxy-1,3-butadiene with (2E)-4-acetoxy-2-methyl-2-octenal dimethyl acetal.