B(C₆F₅)₃-Catalyzed Multicomponent Reactions of 2,3-Diketoesters, Amines, Allenes, and Nucleophiles: Synthesis of 2α-Functionalized Pyrroles

An efficient B(C6F5)3-catalyzed multicomponent reaction of 2,3-diketoesters, amines, allenes, and nucleophiles was reported, which afforded 2α-functionalized pyrroles in moderate to good yields. The reaction features low catalyst loading, usage of a small amount of solvent, high atom economy, tunable installation of diverse functional groups at 2α-position, and water being formed as the byproduct. This is the first multicomponent reaction that combines vicinal tricarbonyl compounds with allenes.