PPA-SiO₂–Catalyzed Multicomponent Synthesis of Amidoalkyl Naphthols

Abstract

Silica gel–supported polyphosphoric acid (PPA-SiO₂) was found to be an efficient catalyst for the multicomponent condensation reaction of aryl aldehydes, 2-naphthol, and urea or amides to afford the corresponding 1-amidoalkyl-2-naphthols in good to excellent yields. This new approach consistently had short reaction times, high conversions, clean reaction profiles, and simple experimental and workup procedures.

Keywords:

• Amide
• aryl aldehyde
• multicomponent reaction
• 2-naphthol
• PPA-SiO₂

ACKNOWLEDGMENTS

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

Notes

^a Yield refers to the isolates pure products.

^a Yield refers to the isolated pure products. All known products have been reported previously in the literature and were characterized by comparison of IR and NMR spectra with authentic samples.^[ 6-15 ^]

^b Yield after recovery of catalyst five times.

^a Based on 2-naphthol (1 equiv.), benzaldehyde (1 equiv.) and acetamide (1.2 equiv.).