Chem Sci Trans., 2012, 1(1), 73-84 Chemical Science Transactions DOI:10.7598/cst2012.139 ISSN: 2278-3458 Three-Component Synthesis of α-Amidoalkyl-β-naphthols and α-Carbamato-alkyl-β–naphthols Catalyzed by P 2 O 5 /SiO 2 HAMID REZA SHATERIAN * , KOBRA AZIZI and NAFISEH FAHIMI Department of Chemistry, Faculty of Sciences, University of Sistan and Baluchestan, PO Box 98135-674, Zahedan, Iran hrshaterian@chem.usb.ac.ir Received 6 May 2012 / Accepted 18 May 2012 Abstract: A convenient and efficient solvent-free procedure via a three-component reaction of aldehydes, β–naphthol, and amides or carbamates for preparation of α-amidoalkyl-β-naphthols and α-carbamato-alkyl-β–naphthols in the presence of green catalytic amount of phosphorus pentoxide supported on silica gel (P 2 O 5 /SiO 2 ) is described. The use of non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are the advantages of this method. Keywords: α-Amidoalkyl-β-naphthols, α-Carbamato-alkyl-β–naphthols, Heterogeneous catalyst, P 2 O 5 /SiO 2 ; Solvent-free Introduction The development of cleaner technologies is a major subject in green chemistry 1 . Among the several aspects of green chemistry, the reduction or replacement of volatile organic solvents from the reaction medium is of greatest concern 2 . Heterogeneous organic reactions and solvent-free reactions have many advantages such as reduced pollution, low costs, simplicity in process with ease handling of catalyst, cleaner reactions, easier work up, decreasing corrosive problems, reduced reaction times and eco-friendliness 3 . These considerations are currently driving our efforts to develop heterogeneous organic transformations. Phosphorus pentoxide is a white, flammable, dangerous, corrosive to metal and extremely deliquescent compound 4a . It reacts vigorously with water and water-containing substances, liberates much heat and may even cause fire 4 . Phosphorus pentoxide-methanesulfonic acid was used for the first time as a convenient alternative to polyphosphoric acid by Eaton et al to escape the difficulties encountered with polyphosphoric acid (PPA) 5 . Then, P 2 O 5 supported on SiO 2 as an inexpensive, heterogeneous stable, free flowing, and white powder was prepared 6a . It has the advantage of being easily removed from the organic product by simple filtration and also this reagent is improved storage stability in moisture in comparison to P 2 O 5 , which is very sensitive to moisture and also it showed much more reactivity than unsupported P 2 O 5 6 . This heterogeneous catalyst has been used in several organic reactions such as Fries rearrangement 7 , nitration of aromatic compounds 8 , protection and deprotection of aldehydes 9 , or alcohols 10 , Beckmann or Schmidt rearrangements 11 , preparation of bisindolylmethanes 12 , solvent-free synthesis of N– sulfonyl imines 13 and Ritter reaction 14 . RESEARCH ARTICLE