Copper-Carbene-Triggered Electrophilic Cyclization of o‑Hydroxyarylenaminones with 3‑Diazoindolin-2-imines: Synthesis of 3‑Indolyl‑4H‑chromen-4-ones and Pyrido[2,3‑b:6,5‑b′]diindoles
2019-04-19T00:00:00Z (GMT) by
The Cu(II)-catalyzed electrophilic cyclization reaction between o-hydroxyarylenaminones and 3-diazoindolin-2-imines furnished 3-indolyl-4H-chromen-4-ones in moderate to good yields with a broad substrate scope. Several pyrido[2,3-b:6,5-b′]diindoles and one pyrazino[2,3-b:5,6-b′]diindole were also obtained as byproducts in some cases and tested for their photophysical properties. Pyrido[2,3-b:6,5-b′]diindoles exhibited solvent-dependent emission, while pyrazino[2,3-b:5,6-b′]diindole emitted strong luminescence with 25.6% quantum yield in cyclohexane.