Golden opportunities in catalysis

The gold-catalyzed endo-cycloisomerization of allenes bearing nucleophilic substituents in the alpha- or beta-position opens up a versatile access to various five- and six-membered heterocycles. Key features of these transformations are the high reactivity of the allene in the presence of Lewis-acidic, carbophilic gold(I) or gold(III) catalysts, and the chirality transfer from the allenic axis of chirality to the new stereogenic center in the cyclization product. Recent contributions of our group include the optimization of chirality transfer by using sigma-donor ligands to gold, and applications in the total synthesis of natural products, e.g., of the beta-carboline alkaloids (-)-isocyclocapitelline and (-)-isochrysotricine.