Facile Synthesis of Furowarfarins via Hetero-Diels–Alder Cycloaddition Reaction

Abstract

Synthesis of new furowarfarins has been carried out via tandem Knoevenagel–hetero-Diels–Alder cycloaddition reaction. One-pot, multicomponent reaction involving, heating a mixture of hydroxy chromenone, aldehyde, and 2-methoxy propene afforded pyranochromenone with good diastereoselectivity, favoring the exo (trans) cycloadduct, in contrast to previous literature reports. The pyran ring exists in a half-chair conformation with C9-OMe in ψ-axial and C7-phenyl ring in ψ-equatorial positions. Single-crystal x-ray analysis conclusively confirms the structure.

GRAPHICAL ABSTRACT

Keywords:

• Exo (trans)
• furowarfarin
• half-chair conformation
• Knoevenagel–hetero-Diels–Alder cycloaddition
• x-ray crystallography

ACKNOWLEDGMENTS

The authors are thankful to the head, Department of Chemistry, Maharaja Sayajirao University of Baroda, for providing the necessary facilities. One of the authors (J. M. P.) is thankful to AICTE, New Delhi, for providing financial assistance.

Notes

Crystallographic data (excluding structural factors) for the structure in this article have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication number CCDC 698274.