Different products in the reaction of the alcohols with cyclic and acyclic 1,3-dicarbonyl compounds: K 5 CoW 12 O 40 as an electron transfer nano catalyst Ezzat Rafiee * , Masoud Kahrizi, Mohammad Joshaghani Department of Chemistry, Razi University, Kermanshah 67149, Iran Received 20 August 2012 Available online 20 November 2012 Abstract K 5 CoW 12 O 40 was used as a highly effective catalyst for the benzylation of 1,3-dicarbonyl compounds. b-Keto enol ethers were obtained when cyclic 1,3-dicarbonyl compounds used in this conditions instead of linear ones. The present methodology offers a practical, simple, mild, environmentally friendly, and time-saving method for etherification. Very low loading of catalyst, ease of workup, ease of handling, and reusability of catalyst are other advantages of this catalyst. # 2012 Ezzat Rafiee. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Benzylation; Etherification; b-Keto enol ethers; Nano catalyst; Polyoxometalate Nano-sized catalysts continue to attract interest for different researcher areas due to their different physical and chemical properties when compare to bulk material. The extremely small size of the particles maximized the surface area exposed to the reactant, allowing more reactions to occur at the same time, thus speeding up the process. Catalysis by polyoxometalates and related compounds is a field of increasing importance as nano catalysts [1–3]. They are promising candidates for catalyst design due to their controllable acid and redox properties and have been actually utilized in some industrial processes [4]. As an interesting example, 12-tungstocobaltate(III), [Co III W 12 O 40 ] 5À , having E 0 = 1.07 V (against a normal hydrogen electrode) has been used as an oxidant both for organic and inorganic substances [5,6]. It is apparently a perfect outer-sphere oxidant because the central Co III atom is protected by a sheath of chemically inert oxygen atoms, which protect the central ion from undesired inner-sphere substitution reactions. The self-exchange rate between [Co III W 12 O 40 ] 5À/6À couples found extensive use in the catalytic application [6]. This catalyst showed excellent reactivity in our previous works [7,8] as a heterogeneous catalyst. During the course of our studies directed towards the development of practical and environmentally friendly procedures for some important transformations, we developed the applicability of a recyclable heterogeneous catalyst, potassium dodecatungstocobaltate trihydrate, K 5 CoW 12 O 40 Á3H 2 O (KCoW), for the condensation reaction of alcohols with 1,3-dicarbonyl compound. This reaction offers different products related to the cyclic or linear dicarbonyl compounds. In the presence of linear 1,3-dicarbonyl compound construction of carbon–carbon bonds was happened which is a fundamental task in organic synthesis [9,10]. On the other hand, condensation of cyclic 1,3-dicarbonyl compound with alcohols produce b-keto enol ethers which have been widely used as key intermediates in organic www.elsevier.com/locate/cclet Available online at www.sciencedirect.com Chinese Chemical Letters 23 (2012) 1363–1366 * Corresponding author. E-mail addresses: ezzat_rafiee@yahoo.com, e.rafiei@razi.ac.ir (E. Rafiee). 1001-8417/$ – see front matter # 2012 Ezzat Rafiee. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. http://dx.doi.org/10.1016/j.cclet.2012.10.011