Yb(OTf)₃‐Catalyzed C=C Bond Cleavage‐Reassembly Enabling Bicyclization: Regioselective Synthesis of Heteroarylated Pentacyclic Indoles

Abstract

An Yb(OTf)3‐catalyzed [2+2] cycloaddition /retro‐electrocyclization (CA‐RE)/bicyclization of 1‐(2‐aminoarylaklynyl)‐naphthalen‐2‐ols and 3‐alkylideneoxindoles is reported, enabling a direct C=C bond cleavage‐reassembly process to regioselectively synthesize a variety of quinoline‐tethered benzo[5,6]chromeno[2,3‐b]indoles in 31–84% yields. Exchanging the amino group for a hydroxyl group in the arylalkynyl unit of the naphthalen‐2‐ol substrate resulted in chromenyl chromeno[2,3‐b]indoles via a similar cascade process.