Palladium-Catalyzed Diastereoselective Imidoylative Arylation/Carbamoylation of Conjugated 1,3-Enynes

A three- and four-component construction of heterocycle-substituted allenes through palladium-catalyzed cyclization reactions of 1,3-enyne-decorated isocyanides has been developed. Owing to the strong ability of the isocyano group to coordinate to metal centers, a sequential isocyanide/alkene insertion and 1,3-palladium migration facilitated the formation of an allenyl-palladium intermediate. When aryl boronic acids were applied as the coupling partner, arylated allenes could be synthesized diastereoselectively. The allenyl-Pd species could also be captured by carbon monoxide to afford allenyl amide derivatives via a 4-MCR. Diverse 3,4-dihydropyrrole- and 3H-indole-containing allenes could be rapidly accessed under mild conditions with broad functional group tolerance.