The gold(I)-catalyzed cyclization of 1-(prop-2-yn-1-yl)-2-alkenylbenzenes substituted at the benzylic position with OR groups gives 1,3-disubstituted naphthalenes with concomitant fragmentation of the alkene. One of these annulations proceeds by a retro-cyclopropanation that leads to free gold(I) carbenes.
![Gold-catalyzed annulation/fragmentation: Formation of free gold carbenes by retro-cyclopropanation](https://www.iciq.org/wp-content/uploads/2014/03/Gold-catalyzed-annulationfrag_11811.gif)