Palladium‐Catalyzed Cross‐Coupling of Ynones with Aryl Bromides Enabled by C(O)‐C(sp) Bond Activation

Transition metal-catalyzed cross-coupling reactions have emerged as one of the most attractive methods in organic synthesis in recent years. However, due to the inertness of C-C bonds, C-C bond activation enabled cross-coupling reactions are far less common. In this work, the first example of palladium-catalyzed cross-coupling of ynones with aryl bromides for the synthesis of diarylacetylenes via C(O)-C(sp) bond activation was described. The reaction exhibited directing group-free unstrained C-C bond activation, wide substrate scope, and good functional group tolerance. Preliminary mechanistic studies suggested that a cross-electrophile coupling reaction pathway might be involved rather than the conventional nucleophilic addition/β-C elimination pathway.