Highly Selective One-Pot Coupling Reaction of Indole, Aromatic Aldehydes, and 4-hydroxycoumarin Using Copper Octoate as a Homogeneous Catalyst

Abstract

A facile protocol for the one-pot, multicomponent reaction of indole, 4-hydroxycoumarin, and aromatic aldehydes was developed using copper octoate as an inexpensive, commercially available, and efficient catalyst. This highly selective reaction eliminates the formation of homodimeric by-products (bisindoles and biscoumarins) and selectively results in the formation of heterodimeric adducts containing both indole and coumarin heterocycles.

GRAPHICAL ABSTRACT

Keywords:

• Copper octoate
• 4-hydroxycoumarin
• indole
• multicomponent reaction

Notes

^a Reaction conditions: indole (1 mmol), 4-hydroxycoumarin (1 mmol), aldehyde (1 mmol), 6% xylene solution of copper octoate (0.58 g, 0.1 mmol), n-hexane, reflux.

^b Yields refer to pure products after recrystallization.

^c Min.