Regioselective Synthesis of 3‐(Aryloxyacetyl)‐2,3‐dihydrothieno[2,3‐b][1]benzothiopyran‐4‐ones via Tandem Cyclization

Abstract

2‐[4‐Aryloxybut‐2‐ynylthio][1]benzothiopyran‐4‐ones on treatment with m‐chloroperoxy benzoic acid in chloroform at 0°C to room temperature afforded 3‐(aryloxyacetyl)‐2,3‐dihydrothieno[2,3‐b]benzothiopyrans in 65–70% yield. The sigmatropic [2,3] followed by [3,3] rearrangement, are attributed to this transformation.

Keywords:

• 2‐[4‐Aryloxybut‐2‐ynylthio]benzothiopyran‐4‐ones
• Claisen rearrangement
• Heterocycles
• Phase‐transfer catalysis
• Regioselective synthesis
• [2,3] Sigmatropic rearrangement

Acknowledgments

We are thankful to CSIR (New Delhi) for financial assistance. One of us (SKG) is grateful to CSIR (New Delhi) for a fellowship.