STUDIES IN SIGMATROPIC REARRANGEMENT: REGIOSELECTIVE SYNTHESIS OF THIENO[2,3-b]- THIOCHROMEN-4-ONE DERIVATIVES

ABSTRACT

Thermal rearrangement of a number of 2-(4′-aryloxybut-2′-ynylthio)-thiochromen-4-ones in refluxing chlorobenzene in the presence of catalytic amounts of 4-toluenesulfonic acid afforded 3-aryloxymethyl-2-methylthieno[2,3-b]thiochromen- 4-ones in 55–62% yields.

Keywords:

• Claisen rearrangement
• [3,3]Sigmatropic rearrangement
• Acid catalysis
• Thieno[2,3-b]thiochromen-4-one
• 4-Toluene sulfonic acid

ACKNOWLEDGMENT

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