Synthesis of\nBenzopyrone-Fused Hydrobenzo[<i>c</i>,<i>d</i>]indoles via Cascade Annulation of <i>p</i>‑Quinamines\nand 3‑Formylchromones

A 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed\ncascade annulation\nreaction between <i>p</i>-quinamines and 3-formylchromones\nwas developed, affording a series of benzopyrone-fused hydrobenzo[<i>c</i>,<i>d</i>]indoles in moderate to high yields\nwith excellent diastereoselectivity. This cascade reaction is efficient\nsince two new rings as well as one C–N, one CC, and\ntwo C–C bonds are created in a single step. The scale-up synthesis\nand versatile transformations of the products further demonstrated\nthe practicality and utility of this approach.