Polyaniline salts and complexes: Efficient and reusable catalyst for the one-pot synthesis of 5-(methoxycarbonyl)-6-methyl-4-phenyl-3, 4-dihydropyrimidin-2(1H)-one

Abstract

Polyaniline salts were prepared by doping polyaniline base with different Bronsted acids (sulfuric, nitric, phosphoric, perchloric, hydrochloric acid) and organic acids (p-toluene sulfonic acid, 5-sulfosalicylic acid). Polyaniline complexes were also prepared using Lewis acids (aluminum chloride, ferric chloride). Polyaniline salts and polyaniline complexes were used as catalysts in Biginelli reaction for 5-(methoxycarbonyl)-6-methyl-4-phenyl-3,4- dihydropyrimidin-2(1H)-one synthesis. Benzaldehyde and urea were reacted with methyl acetoacetate using polyani-line-p-toluene sulfonate salt as catalyst with different reaction time, temperature, and amount of catalyst. The use of polyaniline catalysts is feasible because of the easy preparation, easy handling, stability, easy recovery, simple work-up procedure, reusability, excellent activity with less amount of catalyst, and eco-friendly nature. © 2006 Wiley Periodicals, Inc.