Synthesis of Quinolino[3′,4′:4,5]pyrrolo[1,2‐f]phenanthridines by Regioselective Sonogashira Reaction Followed by Domino C–N Coupling/Hydroamination/C–H Arylation

An effective and atom‐economic synthesis of quinolino[3′,4′:4,5]pyrrolo[1,2‐f]phenanthridines has been developed. The protocol involves a site‐selective Sonogashira reaction of 3,4‐dihaloquinoline, followed by a domino C–N coupling/hydroamination/C–H arylation reaction. Quinolino[3′,4′:4,5]pyrrolo[1,2‐f]phenanthridines represent a hitherto unknown class of heterocyclic compounds. A convenient synthesis of quinolino[3′,4′:4,5]pyrrolo[1,2‐f]phenanthridines from alkynylated quinolines is described. The process is mediated by a single palladium catalyst in one step, involving a Buchwald–Hartwig amination followed by a hydroamination and an intramolecular C–H activation step.