A gold(I)-catalyzed cascade reaction for the stereoselective
synthesis of sulfur- or selenium-containing indeno[1,2-b]chromene
derivatives from o-(alkynyl)styrenes substituted at the triple bond with a
thio- or seleno-aryl group is described. The reaction involves a double
cyclization process through a proposed key gold−cyclopropyl carbene
intermediate that evolves by the intramolecular addition of an aromatic to
the cyclopropane ring, affording polycyclic structures. The enantioselective
version was studied using gold(I) complexes bearing chiral ligands.
