ARTICLE Synthesis of novel 5-substituted imidazolinones as insecticides against cotton leaf worm (Spodoptera littoralis) Mamdouh A. Sofan 1 | Tarek M. Abou Elmaaty 2 | Abdel-Kader M. Elkafafy 3 | Ahmed E. M. Abdel Mageed 3 1 Chemistry Department, Faculty of Science, Damietta University, New Damietta, Egypt 2 Faculty of Applied Arts, Damietta University, Damietta, Egypt 3 Plant Protection Research Institute, Agriculture Research Centre, Giza, Egypt Correspondence Mamdouh A. Sofan, Chemistry Department, Faculty of Science, Damietta University, New Damietta 34517, Egypt. Email: masofan1953@du.edu.eg Abstract In the light of using of 5-imidazolinones in agriculture as safe and stable herbi- cides, the pesticide activities of some new synthesized derivatives 3-18 of this ring system against “cotton leaf worm (Spodoptera littoralis)” have been inves- tigated. The interpretation of the elemental and spectral analyses proved the correct structural formulae of the new synthesized compounds. The com- pounds 1, 5, 6a,b, 8a,c, 9, 11, 12, 15, 16, 17, and 18 showed higher potency than chlorpyrifos (dursban) recommended insecticide. While the derivatives 2, 3, 4, 7, 8b, 10, 13, and 14 showed toxicity values less than chlorpyrifos insecti- cide. The 5-imidazolinones 9 and 12 may be potentially used as insecticides for treatment of cotton leaf worm. 1 | INTRODUCTION The significant biological importance of the 5-imidaz- linones in the field of drugs and pharmaceuticals has been described in the literatures. Many heterocyclic compounds containing the 5-imidazolinone as central moiety are used as antitubercular, [1] antihistamine, [2] antimicrobial, [3–5] local anesthetic, [6] sedative and hypnotics, [7] anthel- mintic, [8] antiviral agents. [9] Moreover, oxoimidazolines which are also known as imidazolinones, were found to be exceedingly effective as herbicidal, fungicidal, and vasodila- tor and anticancer agents. [10–16] The imidazolinone herbicides consist of six commer- cial products (Figure 1) with varying levels of crop selectiv- ity and herbicidal activity depending on the chemistry. [17] Each compound of these herbicides is mainly considered as derivative of the parent 2-(4-isopropyl-4-methyl-5-oxo- 4,5-dihydro-1H-imidazol-2-yl)nicotinic acid (or its benzoic acid analog, which is present as a mixture of the m- and p- isomers). [18] These herbicides are utilized in many different crops and production of food and fiber because of their versatil- ity, low toxicity, and environmental safety. Due to their vital roles in agriculture, a great deal of research has been conducted on the efficacy and potential use of these imidazolinones to weed control. [19,20] In the light of these facts, we report here our trial to explore a safe alternative to harmful pesticides for the cotton leaf worm by synthe- sis of some new derivatives of 5-imidazolinones. Insecti- cides are currently the principle method for controlling the Egyptian cotton leaf worm in Egypt and will continue to be used until more biologically based management sys- tems could be developed. [21] Also, this work is mainly focused on the investigation of the toxicity of the synthe- sized compounds against cotton leaf worm (Spodoptera littoralis), and the mechanism of their action will require further study which depends on determining the change of the enzymes of the larvae. 2 | RESULTS AND DISCUSSION 2.1 | Chemistry The synthesis of imidazolin-5-one derivative 2 was car- ried out by reacting of “4-benzylidene-2-phenyloxazol-5 (4H)-one” (1) with ammonium acetate in refluxing gla- cial acetic acid. The oxazolinone 1 was prepared by Received: 22 April 2019 Revised: 29 September 2019 Accepted: 7 October 2019 DOI: 10.1002/jhet.3788 J Heterocyclic Chem. 2020;57:377–389. wileyonlinelibrary.com/journal/jhet © 2019 Wiley Periodicals, Inc. 377