Efficient One-Pot Synthesis of Precursors of Some Novel Aminochromene Annulated Heterocycles via Domino Knoevenagel–hetero-Diels–Alder Reaction

Abstract

An efficient, one-pot synthetic approach to precursors of some new aminochromene/xanthene annulated heterocycles via a tetrabutylammonium hydrogen sulfate–mediated intramolecular domino Knoevenagel–hetero-Diels–Alder reaction is described. The method is general and efficient. The stereochemistry of the product was confirmed by various NMR experiments and single-crystal x-ray diffraction data.

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GRAPHICAL ABSTRACT

Keywords:

• Aminochromene
• 1,3-diketone
• polyheterocycles
• TBA-HS
• xanthene

ACKNOWLEDGMENTS

We sincerely express our thanks to the head, Department of Chemistry, S. P. University, for providing necessary research facilities. Two of us (S. B. T. and H. A. B.) are grateful to the University Grants Commission (UGC), New Delhi, for research fellowships under the UGC scheme of RFSMS.

Notes

^a All reactions were carried out at reflux in CH₃CN with 25 mol% TBA-HS.

^b Isolated yield.

^c Uncorrected.

^d Product decomposed.

^a All reactions were carried out at reflux in xylene with 25 mol% TBA-HS.

^b Uncorrected.