Formal [4+2] Cycloaddition of <i>o</i>‐<i>Aza</i>‐Quinone Methide for the Synthesis of 1,4‐Heterocycle‐Fused Quinolines

Abstract

Abstract A protocol involving intramolecular formal [4+2]‐cycloaddition of in situ generated o‐aza ‐quinone methide for the facile synthesis of 1,4‐heterocycle‐fused quinoline motifs is demonstrated. The cascade involved tandem C−O, C−C, and C−N bond formation and also exhibited excellent functional group tolerance. Enantiomerically enriched 1,4‐oxazepino quinolines were synthesized using alkynols derived from L‐amino acids. The sulfoxide embedded quinolines were transformed to pentacyclic 1,4‐thiepino tethered indeno‐quinoline scaffolds via Pummerer cyclization. magnified image