Research Article Synthesis and Antimicrobial Activity of Some Novel Heterocyclic Candidates via Michael Addition Involving 4-(4-Acetamidophenyl)-4-oxobut-2-enoic Acid Maher A. EL-Hashash, 1 A. Essawy, 2 and Ahmed Sobhy Fawzy 2 1 Chemistry Department, Faculty of Science, Ain Shams University, Cairo, Egypt 2 Chemistry Department, Faculty of Science, Fayoum University, Fayoum, Egypt Correspondence should be addressed to Ahmed Sobhy Fawzy; as1868@fayoum.edu.eg Received 28 May 2014; Revised 12 August 2014; Accepted 20 August 2014; Published 10 September 2014 Academic Editor: Constantinos Pistos Copyright © 2014 Maher A. EL-Hashash et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. his paper discusses the utility of 4-(4-acetamidophenyl)-4-oxobut-2-enoic acid as a key starting material for the preparation of a novel series of pyridazinones, thiazoles derivatives, and other heterocycles via interaction with nitrogen, sulfur, and carbon nucleophiles under Michael addition conditions and studies the antimicrobial activities of some of these compounds. 1. Introduction -Aroylacrylic acid derivatives showed high biological activ- ity and exhibited a broad spectrum of physiological activities [1] (fungicidal, antitumor, hypotensive, hypolipidemic, and antibacterial). Also, -aroylacrylic acids were considered as inhibitors for phospholipase [2, 3] and they have antipro- liferative activity against human cervix carcinoma (Hela cells) [4, 5]. Besides that, -aroylacrylic esters are important intermediates in ield of medical science and agrochem- icals [1]. Chemically, -aroylacrylic acids are convenient polyelectrophilic reagents in the synthesis of heterocyclic compounds, for which the addition of nitrogen, sulfur, phosphorus, or carbon nucleophiles occurs exclusively at the -carbon of the electrophilic center of the molecule [6– 13]. On the other hand, aryl and heteroaryl substituted (E)- 4-oxobut-2-enoic acids and their derivatives represent an important class of compounds with interesting pharmacolog- ical indications including antiulcer and cytoprotective prop- erties [14] and kynurenine-3-hydroxylase [15] and human cytomegalovirus protease inhibiting activity [16]. Also several naturally occurring acylacrylic acids show notable antibiotic activity [17] and they are used as starting materials for the preparation of a novel series of pyridazinones and thiazoles, where many studies have been focused on pyridazinones which are characterized to possess good analgesic and anti- inlammatory activities; besides that, these studies have indicated that the heterocyclic ring substitutions at position six and the presence of acetamide side chain that is linked to the lactam nitrogen of pyridazinone ring at position two of the pyridazinone ring improve the analgesic and anti- inlammatory activities along with nil or very low ulcero- genicity [18]. he aim of this work is to study the behaviour of aza- and carba-Michael addition reactions involving 4-(4-acet- amidophenyl)-4-oxobut-2-enoic acid and nitrogen and/or carbon nucleophiles which is considered as a irst step to prepare pyridazinones, thiazoles, and other heterocyclic compounds. 2. Experimental Melting points were determined on electrothermal apparatus using open capillary method and are uncorrected. Elemental analyses were carried out by the Micro Analytical Center at Cairo University. he IR spectra were recorded on FT/IR- 300E Jasco spectrophotometer as potassium bromide discs. he mass spectra were run by a Shimadzu-GC-MS-QP 1000 EX apparatus at 70 eV. ( 1 H& 13 C) NMR spectra were recorded Hindawi Publishing Corporation Advances in Chemistry Volume 2014, Article ID 619749, 10 pages http://dx.doi.org/10.1155/2014/619749