Divergent synthesis of spiro or fused indole derivatives tethered with seven-membered rings

An efficient divergent synthesis of spiro[furan-2,2′-indolines] fused with seven-membered rings and cyclopenta[b]indoles tethered with 7-oxabicyclo[4.1.1]octanes is described. Spiro[furan-2,2′-indolines] fused with seven-membered rings were obtained with Selectfluor in good to excellent yields, whereas cyclopenta[b]indoles tethered with 7-oxabicyclo[4.1.1]octanes were generated in moderate to good yields in the presence of TBHP and Cu(OTf)₂. The notable strengths of this approach include mild reaction conditions, operational simplicity, and good functional group tolerance.