Domino-Knoevenagel-hetero-Diels–Alder reactions: an efficient one-step synthesis of indole-annulated thiopyranobenzopyran derivatives

Rapid one-step synthesis of hitherto unreported indole-annulated pentacyclic heterocycles containing oxygen, nitrogen, and sulfur has been described by domino-Knoevenagel-hetero-Diels–Alder reaction. The reaction sequence provides a route to the synthesis of a novel type of polyheterocycles in excellent yields with high stereoselectivity.