Indium-Catalyzed Synthesis of 4-Alkynyl-2-quinolones Accompanied by Alkyne Migration

A novel synthetic strategy facilitates the assembly of 4-alkynyl-2-quinolones from α-ketoamides equipped with a tethered alkyne. This process is distinguished by an unexpected internal alkyne migration that effectively relocates the alkyne moiety. Mechanistic insight reveals the intervention of a key allene intermediate, whose isomerization furnishes the product. The Lewis acid catalyst is shown to play a dual role in mediating the overall alkyne-allene-alkyne interconversion. The quinolone products themselves might act as versatile synthetic linchpins, providing diversity-oriented access to a range of complex heterocyclic architectures.