N-Iodosuccinimide: An Efficient Reagent for Regioselective Heterocyclization of 3-Allyl-4-hydroxy[1]benzopyran-2-ones

Abstract

Thermal Claisen rearrangement of 4-allyloxy[1]benzopyran-2-ones in refluxing chlorobenzene gave 3-allyl-4-hydroxy[1]benzopyran-2-ones in 82–90% yield. A number of 3-iodopyrano[3,2-c][1]benzopyran-5(2H)-ones were synthesized in 80–92% yield by the regioselective heterocyclization of 3-allyl-4-hydroxy[1]benzopyran-2-ones with N-iodosuccinimide in acetonitrile at 0–5°C.

Keywords:

• N-Iodosuccinimide
• Regioselective reaction
• Hetero-cyclization
• 4-Hydroxycoumarin
• 6-endo cyclization

Acknowledgment

We thank the CSIR (New Delhi) for financial assistance. P. K. B is grateful to UGC (New Delhi) for a Junior Research Fellowship.