Cationic-Palladium Catalyzed Regio- and Stereoselective Dicarbo-functionalization of Unsymmetrical Internal Alkynes

Reported is the discovery of an approach to regio- and stereoselective syn-1,2-dicarbofuctionalization of unsymmetrical alkynes. A cationic Pd-catalyzed three-component coupling of two distinct carbon-bearing functionalities aryl diazonium salts and aryl boronic acids/olefins with unsymmetrical alkynes enables accessing to all-carbon substituted unsymmetrical olefins. The transformation features broad scope with labile functional group tolerance building a novel chemical space of structural diversity (82 molecules) and is scalable. The cationic Pd species plays crucial; notably, density functional theory (DFT) studies establish this observation. Synthetic versatility of the modifiable carboxylate bearing highly-substituted olefins is also presented.