1526 Synthesis and oxidation of some azole-containing thioethers Andrei S. Potapov *1 , Nina P. Chernova 1 , Vladimir D. Ogorodnikov 2 , Tatiana V. Petrenko 2 and Andrei I. Khlebnikov *1 Full Research Paper Open Access Address: 1 Department of Chemistry, Altai State Technical University, 46 Lenin Ave., 656038 Barnaul, Russia and 2 Institute of Petroleum Chemistry, Siberian Branch of the Russian Academy of Sciences, 3 Akademicheskii Ave., 634055 Tomsk, Russia Email: Andrei S. Potapov * - asp99@yandex.ru; Andrei I. Khlebnikov * - aikhl@chem.org.ru * Corresponding author Keywords: azole; oxidation; sulfone; sulfoxide; thioether Beilstein J. Org. Chem. 2011, 7, 1526–1532. doi:10.3762/bjoc.7.179 Received: 12 September 2011 Accepted: 02 November 2011 Published: 16 November 2011 Associate Editor: D. O'Hagan © 2011 Potapov et al; licensee Beilstein-Institut. License and terms: see end of document. Abstract Pyrazole and benzotriazole-containing thioethers, namely 1,5-bis(3,5-dimethylpyrazol-1-yl)-3-thiapentane, 1,8-bis(3,5- dimethylpyrazol-1-yl)-3,6-dithiaoctane and 1,3-bis(1,2,3-benzotriazol-1-yl)-2-thiapropane were prepared and fully characterized. Oxidation of the pyrazole-containing thioether by hydrogen peroxide proceeds selectively to provide a sulfoxide or sulfone, depending on the amount of oxidant used. Oxidation of the benzotriazole derivative by hydrogen peroxide is not selective, and sulfoxide and sulfone form concurrently. Selenium dioxide-catalyzed oxidation of benzotriazole thioether by H 2 O 2 , however, proceeds selectively and yields sulfoxide only. 1526 Introduction Compounds comprising two pyrazole moieties linked by an ali- phatic spacer act as bidentate chelating ligands, forming complexes with most transition metals and some main-group elements [1]. The coordinating ability of these ligands can be diversified by the introduction of additional donor atoms into the spacer between the heterocycles. Ligands with spacers bearing nitrogen, oxygen, and sulfur atoms have been reported, and some of them were found to be effective inhibitors of steel corrosion [2], while their chromium(III) and palladium(II) complexes demonstrated catalytic activity in ethylene oligomer- ization [3] and Heck cross-coupling reactions [4]. Recently we and others have reported high superoxide dismutase-like activity of copper(II) complexes with bis(pyrazole) ligands [5,6]. Copper(II) complexes with azole-derived thioether ligands were proposed as models for type I copper proteins [7]. The sulfur atom in a thioether spacer gives an additional possi- bility for modification of the ligand structure through its conversion to sulfoxide or sulfone derivatives. In this report we