Gold(I)-Catalyzed Macrocyclization of 1,n-Enynes

The gold(I)-catalyzed [2 + 2] cycloaddn. of large 1,n-enynes (n = 10-16) provides access to 9- to 15-membered ring macrocycles incorporating a cyclobutene moiety, e.g. I. The reaction requires the use of a gold(I) catalyst bearing a sterically hindered biphenylphosphine ligand.