β-Cyclodextrin in Water: Highly Versatile and Green Approach for Biomimetic Regioselective Ring Opening of Chalcone Epoxides with Nitrogen Heterocycles

Abstract

The formation of new C-C bond through highly regioselective ring opening of chalcone epoxides to nitrogen-containing heterocycles has been effectively worked out in impressive yields with heterocyclic nucleophiles such as pyrrole, indole, and 2-methyl indole in the presence of β-cyclodextrin using water as solvent at room temperature within 25–50 min. Water, an environmentally friendly reaction medium, has been utilized for the first time for the reaction of these heterocyclic nucleophiles with chalcone epoxides as their β-cyclodextrin complexes to afford 1,3-diaryl-2-hydroxy-3-(1H-3-indolyl/2-pyrrolyl)propan-1-ones (3a–u). The catalyst can be easily recovered and recycled for several times without loss of activity.

GRAPHICAL ABSTRACT

Keywords:

• β-Cyclodextrin
• chalcone epoxide
• nitrogen heterocycles
• regioselectivity
• water

ACKNOWLEDGMENT

The authors thank the Department of Science and Technology, New Delhi, for providing the HRMS facility.

SUPPLEMENTAL MATERIAL

Characterization data and ¹H and ¹³C NMR spectra associated with this article can be accessed on the publisher’s website.