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.
![Gold(I)-Catalyzed Macrocyclization of 1,n-Enynes](https://www.iciq.org/wp-content/uploads/2014/03/GoldI-Catalyzed_ol-2013-00358f_0009.gif)