Sequential [3,3]Sigmatropic Rearrangement: Regioselective Synthesis of Dimedone‐Annulated Heterocycles

Abstract

The [3,3]sigmatropic rearrangement in the 3‐(4′‐aryloxybut‐2′‐ynyl)mercapto‐5,5‐dimethyl cyclohex‐2‐enones afforded a number of 4‐aryloxymethyl‐7,7‐dimethyl‐6,7,8‐trihydrothiochrom‐3‐en‐5‐ones (70–80%), which underwent second [3,3]sigmatropic rearrangement to furnish benzofuro[3,2‐c][1]‐2,3,4,6,6a,11a‐hexahydro‐3,3,11a‐trimethylthiobenzopyran‐2‐ones (60–70%).

Keywords:

• Claisen rearrangement
• dimidone‐annulated heterocycles
• pterocarpan analogue
• [3,3]sigmatropic rearrangement
• sulfur heterocycles

Acknowledgment

We are thankful to Council of Scientific and Industrial Research (CSIR) (New Delhi, India) for financial assistance. One of us (S. K. S.) is grateful to CSIR for a fellowship.