*Corresponding author: Ali Ramazani Tel: +98 (24) 33052572, Fax: +98 (24) 33052477 Eurasian Chem. Commun., 2019, 117-124 E-mail: aliramazani@gmail.com Page | 117 http://echemcom.com ECC Eurasian Chemical Communications One-pot synthesis of ferrocene-containing 1,3,4-oxadiazole derivatives from N-isocyaniminotriphenylphosphorane (Ph3PNNC), cyclic ketones and ferrocene carboxylic acid Mona Ashtary a , Ali Ramazani *,a,b , Morteza Rouhani c a Department of Chemistry, University of Zanjan, P.O. BOX 45195-313 Zanjan, Iran b Research Institute of Modern Biological Techniques, University of Zanjan, P.O. BOX 45195-313, Zanjan, Iran c Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran Received: 5 July 2017, Accepted: 17 March 2018, Published: 1 January 2019 Abstract Reaction of N-isocyaniminotriphenylphosphorane with cyclic ketones in the presence of ferrocene carboxylic acid proceeded smoothly at room temperature and in neutral conditions to afford ferrocene-containing 1,3,4-oxadiazole derivatives in high yields. The reaction proceeded smoothly and cleanly under mild conditions and no side reactions were observed. The structures of the products were deduced from their IR, 1 HNMR, and 13 CNMR spectra. Keywords: N-isocyaniminotriphenylphosphorane; intramolecular aza-wittig reaction; 1,3,4-oxadiazole; ferrocene carboxylic acid; cyclic ketones. Introduction Multicomponent reaction (MCR) is a synthetic methodology in which the products can be obtained in one pot with much fewer steps [1]. In 1921 Passerini et al. have reported the three- component reaction and Ugi in 1962 reported one-pot condensation of four components [2,3]. Organophosphorus compounds have been extensively employed in organic synthesis, as well as ligands, in a number of transition metal catalysts [4]. Iminophosphoranes are important synthetic intermediates in organic chemistry especially in the preparation of naturally occurring products, compounds with biological and pharmacological activity [5-8]. During recent years, several preparative procedures have been reported for the preparation and synthetic applications of iminophosphoranes [9-11]. The unique synthetic potential of iminophosphoranes results from the presence of electronrich nucleophilic nitrogen atoms and electrophilic phosphorus atoms as P + – N bonds in their structures. The structural properties of the P +– N bond and its chemical reactivity have been investigated through theoretical, spectroscopic and crystallographic investigations [12]. The presence of the P + – N bond in the iminophosphoranes’ structures is a factor of essential mechanistic importance in their applications as aza-Wittig reagents [13]. The intramolecular aza-Wittig Original Research Article