Synthesis of a Full Spectrum of Indole‐Fused Medium‐Sized Lactams via Base‐Enabled Higher‐Order Annulation

An efficient synthesis of indole‐fused medium‐sized lactams via higher‐order annulation is reported. This strategy employs 2‐indolylcarboxylate esters as flexible 4C to 7C synthons, which undergo higher‐order annulations with aza ‐ ortho ‐quinone methides generated in situ from ortho ‐chloromethyl anilines. The method enables access to a full spectrum of indole‐fused eight‐ to eleven‐membered lactams under mild conditions, featuring broad substrate scope and excellent functional group tolerance. This work not only establishes an efficient approach for constructing indole‐fused medium‐sized rings, but also significantly enriches the chemistry of indole‐fused heterocycles.