Regioselective synthesis of pentacyclic heterocycles by the thermal and Lewis acid catalyzed Claisen rearrangement

Abstract

[6,6]- and [6,5]-fused hithero unreported pentacyclic heterocycles have been regioselectively synthesized from 4-(4′-aryloxybut-2′-ynylthio)thiocoumarin in good yields by the application of thermal as well as catalytic Claisen rearrangement.

Keywords:

• Claisen rearrangement
• Lewis acid catalysis
• pyridine hydrotribromide
• regioselectivity

Acknowledgement

We thank the CSIR (New Delhi) for financial assistance. We also thank the DST (New Delhi) for providing us UV-VIS and FT-IR under the FIST program. One of us (A.P.) is grateful to the CSIR for a Senior Research Fellowship.