Synthesis of novel disulfide-bridged dilactam crown ethers Hossein Eshghi * , Seyed Mohammad Seyedi, Reza Sandarooss Department of Chemistry, Ferdowsi University of Mashhad, Mashhad 91775-1436, Iran Received 26 July 2007 Abstract The novel macrocyclic dilactams with redox-switched disulfide linkage were synthesized. These compounds were obtained from 2,2 0 -dithiodibenzoyl chloride in the macrocyclization step by fast addition method in moderate yields. # 2007 Hossein Eshghi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Dilactam; Disulfide; Fast addition; Macrocyclization; Redox; Switchable There have been great advances in the chemistry of sulfur-substituted crown ethers [1]. Thiacrown ethers are known to coordinate to transition metals [1,2] whereas crown ethers prefer to coordinate with alkaline and alkaline earth metals [3]. Application of these compounds to molecular machines and devices has also attracted much attention [4]. In general, redox reactions between dithiol and disulfide are very useful to control molecular structures and functions simultaneously [5]. This phenomena is known to regulate enzymatic activity [6] and ion recognition of artificial hosts [5]. According to design and synthesis of several redox-switched crown ethers with disulfide linkage are reported, for examples, for zinc abstraction from proteins and disrupt their conformation for achieving maturation of HIV virus [7], paraquat and secondary ammonium salts recognitions [8], and selective electrode properties in laboratory [9] and in the biomembranes [10]. Here we report the synthesis of novel macrocyclic dilactams with disulfide linkage (2–7). In these switchable crown compounds, the 2,2 0 -dithiobisbenzamides were used as the constructing part of the systems which recently have been used as anti-HIV-1 agents [7]. 1. Experimental All materials and solvents were obtained from Merck chemical company (Germany) and Fluka (Switzerland). Melting points were determined in open capillary tubes in an Electrothermal IA 9000 melting point apparatus. IR spectra were recorded on a Shimadzu-IR 470 spectrophotometer. 1 H and 13 C NMR spectra were recorded on a Bruker- 500 MHz and Bruker-100 MHz instruments using tetramethylsilane (TMS) as an internal standard. Mass spectra were determined on a Shimadzu GCMS-QP 1000 EX instrument at 70 eV. www.elsevier.com/locate/cclet Available online at www.sciencedirect.com Chinese Chemical Letters 18 (2007) 1439–1442 * Corresponding author. E-mail address: heshghi@ferdowsi.um.ac.ir (H. Eshghi). 1001-8417/$ – see front matter # 2007 Hossein Eshghi. Publishedby Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2007.10.027