Convenient access to asymmetric 7– and 8–membered carbocycles is possible using chiral BINAP Au(I) gold catalyst, giving a wide variety of products. It is proposed that intramolecular cyclopropanation occurs via a 1,2–shift of the propargyl ester mediated by Au to give a "syn"–Au vinyl carbenoid species (29). Computational studies show that the "syn"–intermediate, 29, is formed under kinetic control and it is suggested that it is in equilibrium with the thermodynamically favorable "cis"–intermediate which may be intercepted by a nucleophile leading to vinyl cyclopropane diene products, however this is beyond the scope of this article. Vinylcycloalkenes is another functional class of products accessible through alkyne activation of enynes with π–acidic metals. PtCl2 has been shown to catalyze the formation of a variety of exotic vinylcycloalkenes from readily accessible starting materials (figure 10). Notably, a ring expansion is observed for enynes with cyclic alkene motifs. This is rationalized by a formal insertion of the methylene group of the olefin between the two carbons of the alkyne; a mechanistic reasoning for this ring expansion has also been proposed. The formation of these vinycloalkenes in concert with its ability to undergo a ring expansion was exploited to construct intermediate 36 "en" route to streptorubin B. A similar transformation is possible using cationic Au(I) complexes, however here one can select for vinycycloalkene products through a mechanism proceeding via an initial "5–exo–dig" or bicyclepropanes can be produced via an initial "6–endo–dig". It is suggested through DFT calculations that the "5–exo–dig" cyclization is favored for Au(I) complexes as it has a lower activation barrier relative to the "6–endo–dig" and indeed numerous examples of vinylcycloalkenes products produced via an initial "5–exo–dig" are given (figure 11). The reactivity can be reversed by careful selection of reaction conditions, catalyst selection and substrate. The divergent reactivity of these transition metal catalyzed cyclosiomerizations further demonstrates their synthetic utility in building unique molecular skeletons.