Sulfonyl Ketenimines as Key Intermediates in One-Pot Synthesis of N-Sulfonyl-2-alkaneimidoyl Selenocyanates by Issa Yavari*, Zohreh Taheri, Manijeh Nematpour, and Azam Sheikhi Departmentof Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran (phone: þ 98-21-82883465; fax: þ 98-21-82883455; e-mail: yavarisa@modares.ac.ir) Sulfonyl-ketenimine intermediates, generated by the addition of Cu acetylides to sulfonyl azides, are trapped by KSeCN to afford N-sulfonyl-2-alkaneimidoyl selenocyanates in moderate-to-good yields. Introduction. – Selenium is a trace element, essential for normal human develop- ment, growth, metabolism, and function of the immune system. Originally, Se was considered as one of the most toxic elements. Its benefits were not fully appreciated until 1957, when Schwarz and Foltz described the relationship between Se intake by food and prevention of liver necrosis in rats [1]. In 1973, it was discovered that Se is a part of glutathione peroxidases (GSHPx), antioxidant proteins that reduce potentially damaging reactive oxygen species (ROS), such as H 2 O 2 and lipid hydroperoxides, to harmless products [2]. In recent years, increasing attention has been paid to Se- containing compounds due to their use as synthetic tools [3] and as promising biologically active substances [4] [5]. Recently, we reported that ketenimine intermediates generated by the addition of Cu acetylides to sulfonyl azides are trapped by KSCN to afford 1-thiocyanato-N- sulfonylalkan-1-imine derivatives [6]. Herein, we report a simple and efficient procedure for the synthesis of N-(alkyl- or arylsulfonyl)alkaneimidoyl selenocyanate derivatives 4 via the Cu-catalyzed three-component coupling reaction of sulfonyl azides, terminal alkynes, and KSeCN ( Table). Results and Discussion. – Initially, phenylacetylene (1a), tosyl azide (2a), and KSeCN were selected as model substrates. Several catalysts such as CuI, CuBr, CuCl, Cu 2 O, and Cu powder were tested, with CuI giving the best results. Among several solvents screened, DMF turned out the best. When the reaction was performed in DMF in the presence of 1 equiv. of Et 3 N at room temperature for 8 h, selenocyanate 4a was obtained in 82% yield. Thus, the optimized reaction conditions used were 10 mol-% of CuI, 1 mmol of alkyne, 1.2 mmol of sulfonyl azide, and 1.5 mmol of KSeCN in 3 ml of DMF at room temperature. Aliphatic acetylenes served as low-yielding substrates compared to phenylacety- lene. Aromatic and aliphatic sulfonyl azides reacted efficiently, and the corresponding products were obtained in good yields. Helvetica Chimica Acta – Vol. 98 (2015) 343  2015 Verlag Helvetica Chimica Acta AG, Zürich