Solvent-free one-pot synthesis of 2-pyridone derivatives Zinatossadat Hossaini a, * , Faramarz Rostami-Charati b , Rahimeh Hajinasiri a , Mohammad A. Khalilzadeh a a Department of Chemistry, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran b Department of Chemistry, Faculty of Science, Gonbad Kavous University, P.O. Box 163, Gonbad, Iran Received 14 November 2011 Available online 7 April 2012 Abstract An efficient synthesis of methyl 4-hydroxy-6-oxo-1,6-dihydro-2-pyridine carboxylates is described. This involves three component reactions between primary alkyl amines, malonyl dichloride and methyl propiolates. # 2012 Zinatossadat Hossaini. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: One-pot reactions; Multicomponent reactions; Methyl propiolate; Green chemistry The methods of green chemistry continue to grow in importance. Alternative processes help to conserve resources and can even reduce costs. The replacement of convention solvents with water or solvent-free conditions, which is harmless to health and is available in large quantities, is one of the most interesting basic approaches along these lines. The 2-pyridone core structure is an important heterocyclic framework that can be found in numerous biologically active compounds. It is also a versatile synthon that can be further transformed to pyridine, piperidine, quinolizidine, and indolizidine alkaloids [1]. N-Alkylated 2-pyridones are important intermediates in the synthesis of polycyclic compounds of biological significance [2]. The broad range of applications of the 2-pyridone structural motif has resulted in several synthetic methods [3]. The most versatile and useful strategy to produce pyridine derivatives is condensation between 1,3-dicarbonyl compounds and 3-aminoenones,3-aminoacrylates, or cyanoacetamides [4,5]. Recently, multicomponent condensation reactions have become a powerful method for the synthesis of small- molecule libraries, due to the fact that products are formed in a single step by simultaneous reactions of several reagents and the molecular diversity required for such combinatorial libraries can be achieved by simply varying each component [6–8]. Herein, we describe an efficient synthesis of functionalized 2-pyridones via the reaction of alkyl amines 1 with methyl propiolate 2 in the presence of malonyl dichloride 3 under solvent-free conditions at 508C (Scheme 1). The structures of compounds 4a–g were apparent from the 1 H NMR, 13 C NMR and IR spectra which are in agreement with the proposed structures [9]. The 1 H NMR spectrum of 4a in CDCl 3 showed five singlets for methoxy (d 3.75), methylene (d 5.20), methine (d 6.12 and 6.27), and OH (d 10.75) protons, along with characteristic multiplets for the aromatic protons. The 13 C NMR spectrum of 4a exhibited 12 signals in agreement with the proposed structure. www.elsevier.com/locate/cclet Available online at www.sciencedirect.com Chinese Chemical Letters 23 (2012) 512–514 * Corresponding author. E-mail address: zshossaini@yahoo.com (Z. Hossaini). 1001-8417/$ – see front matter # 2012 Zinatossadat Hossaini. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2012.01.018