FeCl₃-Catalyzed Cascade Reaction: An Efficient Approach to Functionalized Coumarin Derivatives

Abstract

An efficient and environmentally benign synthesis of 3-substituted or 3,4-disubstituted coumarins was accomplished via iron(III) chloride–catalyzed cascade reactions of salicylaldehydes and activated methylene compounds. The reaction preceded cleanly under mild reaction conditions to provide the desired coumarin derivatives in good to excellent yields.

GRAPHICAL ABSTRACT

Keywords:

• Activated methylene compounds
• cascade reaction
• catalysis
• coumarins
• iron(III) chloride

Notes

^a Reaction conditions: 1a (1.0 mmol), 2a (1.0 mmol), solvent (5 mL), 80 °C.

^b Yield of the isolated product.

^a Reaction conditions: 1 (1.0 mmol), 2 (1.2 mmol), FeCl₃ (0.05 mmol), EtOH (5 mL), 80 °C, 24 h.

^a Reaction conditions: 1 (1.0 mmol), 2 (1.2 mmol), FeCl₃ (0.05 mmol), EtOH (5 mL), 80 °C, 24 h.

^b Methanol as solvent.

^c Na₂CO₃ (1.0 mmol) was used as an additive.

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