Rhodium(I)-catalyzed C–C bond activation : decarbonylation of α,β-acetylenic ketones

Transition metal-catalyzed carbon–carbon (C–C) bond activation is a useful way to construct organic molecules that could be difficult or impossible to achieve under traditional synthetic conditions. Many novel transformations have been reported utilizing strained systems or directing groups to undergo C–C activation, but far fewer have been described for non-strained, non-chelated systems. One example that avoids strain or directing groups is carbon–cyanide activation, which has been well developed and is quite versatile. Considering the analogous structure of C–C≡C bonds, a long standing goal has been to activate carbon–alkyne bonds. Up to now, catalytic methods to achieve this goal have not been reported. Herein, rhodium(I)-catalyzed carbon–alkyne activation of α,β-acetylenic ketones is described. The products from these transformations have undergone decarbonylation to form 1,3-diynes, 1,2-disubstituted alkynes, and ynones. In addition to the substrate scope, the mechanism and potential applications will also be discussed.