Heterobimetallic Pd–Sn Catalysis: A Suzuki, Tandem Ring-Closing Sequence toward Indeno[2,1‑<i>b</i>]thiophenes and Indeno[2,1‑<i>b</i>]indoles

Indeno[2,1-<i>b</i>]thiophene and indeno[1,2-<i>b</i>]indole motifs have been obtained in moderate to good yields from easily available substituted boronic acids, 2-bromo aryl/vinyl aldehydes, and nucleophiles such as arenes/heteroarenes and others using a catalytic combination of bimetallic “Pd–Sn” and AgPF₆. This formal three-component coupling involves a Suzuki reaction followed by nucleophile assisted tandem ring closure. The sequential synthesis of substituted heterocycle-fused indenes, benzofluorene, and fluorenes was also accomplished