Intermolecular cyclopropanation reactions of enynes with alkenes allows the synthesis of complex cyclic systems with gold(I) catalysts under mild conditions. Furthermore, gold carbenes are trapped intermolecularly with alkenes (see scheme; L=ligand), thereby providing experimental evidence for the involvement of two different types of metal carbenes in the skeletal rearrangement of enynes.
![Gold(I)-catalyzed intermolecular cyclopropanation of enynes with alkenes: trapping of two different gold carbenes](https://www.iciq.org/wp-content/uploads/2014/03/GoldI-catalyzed_eng_noticies_articles_2006_18.gif)