Short communication Grinding-induced rapid, convenient and solvent free approach for the one pot synthesis of a-aminophosphonates using aluminium pillared interlayered clay catalyst Bashir Ahmad Dar a , Arup Chakraborty a , Parduman R. Sharma a , Varsha Shrivastava a , Amrita Bhowmik a , Dushyant Vyas a , Prince Bhatti a , Meena Sharma b, *, Baldev Singh a, * a Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu 180001, Jammu & Kashmir, India b Department of Chemistry, University of Jammu, Jammu & Kashmir 180004, India 1. Introduction Being bioisosteres of natural amino acids, a-aminophospho- nates have been found to exhibit pivotal role in various medicinal aspects owing to its fascinating array of multifarious potential therapeutic activities, such as anticancer agent [1], antithrombotic agent [2], antibiotic [3], potential antioxidants [4], haptens of catalytic antibodies [5], biotryticides [6], enzyme inhibitors [7], catalytic antibodies [8], anti-inflammatory agent [9], antihyper- tensive agents [10], carriers of hydrophilic organic molecules across phospholipid membrane [11] etc. They also exert their action as hypothetical radio protecting agent [12], herbicides [13], plant virucides [14], fungicides [15] and insecticides [16]. This brings a-aminophosphonate and its derivatives to a great prominence, which have made the researchers intrigued to know the best methods for their synthesis. Albeit a wide variety of approaches has been facilitated for the one-pot synthesis of a- aminophosphonates using several acid catalysts, such as Lewis acids {Na 2 CaP 2 O 7 [17], Al(H 2 PO 4 ) 3 [18], BiCl 3 [19], Bismuth nitrate pentahydrate [20], trimethylanilinium chloride [21], (bromodi- methyl) sulfonium bromide [22]} or Bronsted acids {oxalic acid [23], hypophosphorus acid [24], sulfamic acid [25]}, base catalysts such as CaCl 2 [26] etc., but none of them display efficient methodology precluding the use of auxiliary substances (e.g., solvents, additional reagents, special apparatus) and costly and moisture sensitive catalysts, minimizing tedious experimental procedure and energy requirement. Recently on viewing the cons of using those catalysts, methodologies with some other catalysts, for instance ammonium metavanadate [27], FeCl 3 [28], Amberlyst- 15 [29], nano CeO 2 [30], CeCl 3 Á7H 2 O [31], CdI 2 [32], BF 3 -SiO 2 [33], NbCl 5 [34], TsCl [35], ZrOCl 2 Á8H 2 O or ZrO(ClO 4 ) 2 Á6H 2 O [36] etc., have been developed. But due to stringent and growing environmental regulations, the chemical industry needs the development of more environmentally benign alternative methods which can be achieved by using modified clay catalysts. Clays have been modified to act as acid–base combination catalysts which turn it up in acid and base-catalyzed reactions in a sequence in one-pot. Much of work on clays focus on the use of ‘normal’ smectites, mostly the commercially available K10 and KSF or native varieties with Bronsted or Lewis acid sites and enhancing their catalytic performance by pillaring techniques to manipulate the pore size, surface area and replace interlayer cations to alter acid–base properties. Impressed with the proper- ties of clays straightforward synthetic approach to a-aminopho- sphonates and in continuation to our interest in heterogeneous catalysis [37] and a-aminophosphonate chemistry [38] we have Journal of Industrial and Engineering Chemistry xxx (2012) xxx–xxx A R T I C L E I N F O Article history: Received 19 September 2012 Accepted 20 October 2012 Available online xxx Keywords: a-Aminophosphonates Green synthesis Heterogeneous catalyst Grindstone chemistry Pillared interlayered clay A B S T R A C T An easy to prepare aluminium pillared interlayered clay (PILC) has been developed as a stable, recyclable and heterogeneous catalyst to promote the one-pot three component synthesis of a-aminopho- sphonates under solvent-free conditions using grindstone chemistry. Utilization of mild reaction conditions, clean conversion and greater selectivity under grinding conditions along with effortless separation, and purification of reaction products make this process extra attractive. ß 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved. * Corresponding authors. Tel.: +91 2572002; fax: +91 2548607. E-mail address: drbaldev1@gmail.com (B. Singh). G Model JIEC-1098; No. of Pages 7 Please cite this article in press as: B.A. Dar, et al., J. Ind. Eng. Chem. (2012), http://dx.doi.org/10.1016/j.jiec.2012.10.018 Contents lists available at SciVerse ScienceDirect Journal of Industrial and Engineering Chemistry jou r n al h o mep ag e: w ww .elsevier .co m /loc ate/jiec 1226-086X/$ – see front matter ß 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jiec.2012.10.018