Microwave-Assisted K-10 Montmorillonite Clay–Mediated Knoevenagel Hetero-Diels–Alder Reactions: A Novel Protocol for the Synthesis of Polycyclic Pyrano[2,3,4-<i>kl</i>]xanthene Derivatives

Abstract

Abstract The intramolecular hetero-Diels–Alder reactions of 2-(cyclohex-2-enyloxy)benzaldehyde by Knoevenagel condensation with symmetrical 1,3-diones under three different conditions afforded the pyrano[2,3,4-kl]xanthene derivatives in a stereoselective manner in good yield. The structure of one of the products was unambiguously established by x-ray analysis.