Dodecatungestophosphoric acid (H 3 PW 12 O 40 ) as a solid green Brønsted acid catalyzes high yielding and efficient trimethylcyanosylilation reactions of aldehydes and ketones by trimethylsilyl cyanide Habib Firouzabadi * , Nasser Iranpoor * , Abbas Ali Jafari Department of Chemistry, Shiraz University, Shiraz 71454, Iran Received 11 September 2004; accepted 20 December 2004 Available online 19 January 2005 Abstract An efficient solvent-free method is described for the addition of TMSCN to carbonyl groups employing dodecatungestophos- phoric acid (H 3 PW 12 O 40 ) as a heterogeneous and environmentally benign catalyst. By this method, aromatic, aliphatic, cyclic and heterocyclic aldehydes and ketones are converted into their corresponding cyanotrimethylsilyl ethers in excellent yields (89– 98%) in short reaction times (<10 min). Ó 2004 Published by Elsevier B.V. Keywords: Dodecatungestophosphoric acid; Aldehyde; Ketone; Cyanotrimethylsilyl ethers 1. Introduction The development of practical protocol for the prepa- ration of a-hydroxy-, a-substituted acids, ketones, alde- hydes, and a-hydroxy amines from readily available carbonyl compounds is an important achievement in or- ganic synthesis. One of the most straightforward entries to this important goal is through their cyanohydrin preparations [1]. They are also components of commer- cially important compounds such as the pyrethroid insecticides, cypermetrin and fluvaliate [2]. Preparation of cyanohydrins by the addition of highly toxic HCN to carbonyl group is not a straightforward process and the procedure should be undertaken with caution. The other problem which affects the yields of the products stems from the existence of inevitable equilibrium condi- tion between the reactants and the adduct product. In order to surmount this problem, the reaction of TMSCN with carbonyl groups in the presence of Lewis acid or Lewis base catalysts has been under attention in the last decade [3]. Very recently new catalysts such as; indium tribromide [4a], layered zirconium hydrogen phosphate [4b], and several N-oxide compounds [4c–h] have been reported for this purpose. However, general, mild, and high-yielding processes for cyanation of hin- dered carbonyl groups are still very limited in the literature. Development of methods using heteropolyacids (HPAs) as catalysts for fine organic synthetic pro- cesses related to fine chemicals, such as flavors, phar- maceuticals and food industries [5] have been under attention in the last decade. Heteropolyacids are more active catalysts than conventional inorganic and or- ganic acids for various reactions in solution [6]. They are used as industrial catalysts for several liquid-phase 0022-328X/$ - see front matter Ó 2004 Published by Elsevier B.V. doi:10.1016/j.jorganchem.2004.12.025 * Corresponding author. Tel.: +987112284822; fax: +987112280926. E-mail address: firouzabadi@chem.susc.ac.ir (H. Firouzabadi). Journal of Organometallic Chemistry 690 (2005) 1556–1559 www.elsevier.com/locate/jorganchem