Palladium-Catalyzed C–C Bond Activation of Cyclopropenone: Modular Access to Trisubstituted <i>α,β</i>-Unsaturated Esters and Amides

Strain-driven palladium/N-heterocyclic carbene-catalyzed C–C bond activation of diphenylcyclopropenone (DPC) has been explored for one-step access to trisubstituted α,β-unsaturated esters and amides. The designed transformation works under mild conditions providing exclusively a single stereoisomer. Mechanistic studies support the oxidative addition of the C–C bond of cyclopropenone to in-situ-generated Pd(0) intermediate. We have proved that vinylic hydrogen in the product is coming from phenol/aniline through deuterium-labeling studies. Late-stage functionalization of bioactive molecules such as procaine, estrone, and hymecromone demonstrates the robustness of this protocol.