Access to Substituted Dihydrothiopyrano[2,3‑<i>b</i>]indoles via Sequential Rearrangements During <i>S</i>‑Alkylation and Au-Catalyzed Hydroarylation on Indoline-2-thiones

An efficient methodology for the synthesis of indole-fused dihydrothiopyrans has been developed from indoline-2-thiones. The protocol involves the synthesis of conjugated ene-yne-substituted indole-sulfides, a gold­(III)-catalyzed rearrangement of the ene-yne side chain followed by intramolecular hydroarylation via C3–H functionalization of the indole core. This new synthesis of functionalized tricyclic indole derivatives through sequential rearrangements is quite general in nature