Amberlite IRA-400 (OH⁻) as a Catalyst in the Preparation of 4H-Benzo[b]pyrans in Aqueous Media

Abstract

A quaternary ammonium hydroxide–type of anion exchange resin (Amberlite IRA-400) was found to be an effective and reusable catalyst for the synthesis of various 4H-benzo[b]pyran derivatives via a one-pot, three-component condensation in aqueous media. Short reaction time, easy and quick isolation of the products, environmentally friendly procedure, excellent chemoselectivity, and excellent yields are the main advantages of this procedure.

Keywords:

• Amberlite IRA-400
• aqueous media
• 4H-benzo[b] pyrans
• dimedone
• ion-exchange resins

ACKNOWLEDGMENT

We are thankful to the Razi University Research Council for partial support of this work.

Notes

^a Reaction conditions: The reactions were performed with benzaldehyde (1 mmol), dimedone (1.1 mmol), and malononitrile (1.2 mmol) for 16 min at 25 °C.

^b Isolated yield.

^a The aldehyde (1 mmol) was treated with dimedone (1.1 mmol) and malononitrile (1.2 mmol) in the presence of Amberlite IRA-400 (OH⁻) (0.1 g, containing 0.1 mmol of OH⁻) in water (3 mL) at 25 °C.

^b The products were characterized by comparison of their spectroscopic and physical data with those reported in the literature.

^c Yields refer to pure isolated products.

^a Tetra-methyl ammonium hydroxide.

^b Ytterbium perfluorooctanoate.