Homogeneous gold catalysts are interesting as they can act as potent carbophilic Lewis acids to activate the π bonds of alkynes, allenes, and alkenes. Many impressive applications for the formation of C-C or C-heteroatom bonds have been found due to the excellent functional group compatibility of these catalysts and the air and moisture tolerance of their reactions. Here, we have developed gold-catalyzed novel intramolecular cycloisomerizations of nitrogen or oxygen-tethered cyclopropenes with propargylic esters. The reaction proceeded through different pathways according to different substituent styles, affording 5-azaspiro[2.5]oct-7-enes and bicyclo[4.1.0]heptanes.
Keywords: cationic intermediates; cyclopropenes; gold carbenes; gold catalysis; propargylic esters.