Cross-aldol and Knoevenagel condensation reactions in aqueous micellar media Janhavi J. Shrikhande, Manoj B. Gawande, Radha V. Jayaram * Department of Chemistry, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai 400 019, India Received 30 August 2007; received in revised form 28 September 2007; accepted 1 October 2007 Available online 6 October 2007 Abstract Cross-aldol condensation of aromatic aldehydes with cyclic ketones in a micellar medium afforded a,a 0 -bis (substituted benzylidene) cycloalkanones in high yields. Knoevenagel condensation carried out in micellar media is observed to be faster than that in the aqueous solution. The present method is operationally simple and the use of water as the reaction medium makes the process environmentally benign. Ó 2007 Elsevier B.V. All rights reserved. Keywords: Cross-aldol condensation; Knoevenagel condensation; Surfactant; Micellar medium; a,a 0 -Bis (substituted benzylidene) cycloalkanones 1. Introduction One of the fundamental challenges and ultimate goals for the reactions of organic molecules is to perform the reaction in water [1,2], because in comparison with organic solvents, water is cheap, safe and leads to the development of environmentally friendly chemical process [3–5]. However, the major drawback of aqueous media is the limited solubility of various organic compounds in water. This limitation can be overcome by using aqueous surfac- tant solutions in the form of micelles, which can solubilize the substrates [6]. In such cases the observed increase in the reaction rates result from the localized concentration or microcompartmentalization of the reactants by solubiliza- tion, counter ion binding as well as the fact that the micelles may provide an environment more conducive to the desired reaction, without requiring addition of an organic solvent. The solubilization of reactants and prod- ucts inside the micelles not only results in high concentra- tion within the small volume, but the different orientations of the solubilizates may also significantly influ- ence the reaction mechanism, resulting in much different reaction rates and selectivity than that would be observed in a homogeneous system [7]. Herein, we report two impor- tant organic reactions viz., cross-aldol condensation of aro- matic aldehydes with cyclic/acyclic ketones and Knoevenagel condensation of aromatic aldehydes with active methylene reagents in micellar media. Cross-aldol condensation of aromatic aldehydes with cyclic ketones is an important synthetic reaction for the preparation of a,a 0 -bis cycloalkanones. These benzylidene derivatives are important precursors for the synthesis of bioactive pyrimidine derivatives [8]. They also play an important role as intermediates of perfumes [9], pharma- ceuticals, and agrochemicals. When the aldol condensation is classically carried out using an acid or base catalyst [10], the process suffers from side reactions such as self condensation, thus resulting in low yield of the desired product. Different complexes of divalent metal ions such as Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) have also been used as catalysts for the condensation reactions [11]. Other catalysts like bis(p-eth- oxyphenyl) telluroxide (BOMPTO) [12], Cp 2 ZrH 2 [13], Cp 2 TiPh 2 [14], TiCl 3 (SO 3 CF 3 ) [15], KF-Al 2 O 3 [16], FeCl 3 1566-7367/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.catcom.2007.10.001 * Corresponding author. Tel.: +91 22 24145616; fax: +91 22 24145614. E-mail addresses: janhavi.shrikhande@gmail.com (J.J. Shrikhande), rvjayaram@udct.org (R.V. Jayaram). www.elsevier.com/locate/catcom Available online at www.sciencedirect.com Catalysis Communications 9 (2008) 1010–1016