Cycloisomerization of Dienes with Carbophilic Lewis Acids:  Mimicking Terpene Biosynthesis with Pt(II) Catalysts

Dicationic Pt(II) complexes containing triphosphine pincer ligands are excellent catalysts for the cycloisomerization of 1,6- and 1,7-dienes into bicyclopropane carbocycles. In analogy to the biosynthetic route to these monoterpene-like compounds, carbocation intermediates are proposed and supported by trapping experiments. Re-activation of the trapped intermediates indicate that cation generation by C-C bond formation is both rapid and reversible