Regio-controlled synthesis of pyrido[1,2-a]indoles via a palladium-catalysed dual acetylene incorporation approach.

A one-pot palladium-catalysed annulation of readily available 2-iodo-1H-indoles and silyl acetylenes enables direct access to structurally and electronically diverse pyrido[1,2-a]indole derivatives through a regio-controlled sequential double insertion process. The use of a silver salt suppresses the conventional Sonogashira coupling pathway and promotes distinctive annulation reactivity in a single operation.