Environmentally Friendly Preparation of Amidoalkyl Naphthols

Abstract

A new, facile, and cost-effective process involving the solvent-free synthesis of amidoalkyl naphthols using a three-component, one-pot condensation reaction of β-naphthol, aromatic aldehyde, and amides in the presence of Al(H₂PO₄)₃ as heterogeneous catalyst under thermal conditions and microwave irradiation has been described. This new approach has the advantage of consistently excellent yields and short reaction times. The catalyst has shown a very stable catalytic activity in the reaction conditions and also can be recovered and recycled.

Keywords:

• Aluminum tris(dihydrogen phosphate)
• amidoalkyl naphthol
• heterogeneous catalyst
• multicomponent reaction
• solvent-free

ACKNOWLEDGMENTS

We are thankful to the Sistan and Baluchestan University Research Council for the partial support of this research.

Notes

^a The molar ratio of benzaldehyde/2-naphthol/acetamide is 1/1/1.2.

^b Yields refer to pure isolated product.

^a The molar ratio of benzaldehyde/2-naphthol/acetamide is 1/1/1.2.

^b Yields refer to the pure isolated products.

^a Yields refer to the pure isolated products. All known products have been reported previously in the literature and were characterized by comparison of IR and NMR spectra with authentic samples.

^b Yield after five recoveries of the catalyst.

^a Based on 2-naphthol, benzaldehyde, and acetamide.