Palladium-Catalyzed Three-Component 1,4-Carboarylation of 1,3-Enynes with Malonic Esters and Aryl Iodides

Abstract Ionic 1,4-difunctionalization of 1,3-enynes has often been conducted with strong nucleophiles or 1,3-enynes that are activated by an electron-withdrawing group. In this work, a palladium-catalyzed three-component ionic 1,4-carboarylation of 1,3-enynes is reported with arylated 1,3-enynes as the substrates. This method can afford various tetrasubstituted allenes with different functionalities. The palladium salt might play a key dual role in the reaction: as the catalyst to catalyze the cross-coupling reaction and as a Lewis acid to facilitate the nucleophilic attack. The synthetic value of this method is demonstrated by the further cyclization, decoration, and hydrolysis of the allene products.