Cu(OTf)2 Enhanced Intramolecular Nucleophilic N‑Arylation of 2‑Amino-3-arylquinolines

In the presence of Cu­(OTf)2 (5 mol %) and KOtBu, a synergistic effect of the N-arylation process on 2-amino-3-arylquinolines is observed. Within 4 h, this method provides a wide variety of norneocryptolepine analogues with good to excellent yields. Overall, a double heteroannulation strategy for the synthesis of indoloquinoline alkaloids from nonheterocyclic precursors is demonstrated. Mechanistic investigations establish that the reaction proceeds via the SNAr pathway. Despite moderate yields, the one-pot, two-step double heteroannulation illustrates that this procedure is highly atom-efficient. Neocryptolepine, a natural product, is also synthesized from indoloquinoline. A brief study of the photophysical properties of selected norneocryptolepine analogues is also discussed.