IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 03 Issue: 08 | Aug-2014, Available @ http://www.ijret.org 1 MICROWAVE ASSISTED ECO FRIENDLY SYNTHESIS OF 2H- PYRIDO [1, 2-a] PYRIMIDINE-2-ONE Sharulatha V 1 , Indumathi U 2 , Priyadharshini S 3 1 Assistant professor, Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore 2 Research Scholar, Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore 3 Research Scholar Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore Abstract Pyrido primidines are important class of heterocylic compounds because of their use in medicinal and agro chemistry as scaffolds for active agents such as antiviral, antiulcer, antimalarial, antifungal and herbicidal agents. Herein we report the synthesis of 2H- pyrido[1,2-a]pyrimidine-2-ones by the reaction of itaconic acid with 2-amino pyridine in tow steps under classical and microwave technology. Keywords: microwave synthesis 2H-pyrido [1, 2-a] pyrimidine-2-one --------------------------------------------------------------------***------------------------------------------------------------------ 1. INTRODUCTION The organic reactions under microwave irradiation are more advantageous over the conventional methods, owing to shortening of reaction time, mild temperature conditions, and good-to-high yield[1], eco-friendliness and non-use of expensive reagents [2]. The pyrimidine framework is an important structural moiety present in various biologically active molecules including DNA and RNA[3]. Benzo- and hetero-fused pyrimidines are known to exhibit promising antiviral, antiabacterial, anti-AIDS, and antinociceptive activities. The relevance of fused pyrimidines as antiplatelet and antithrombotic drugs has been firmly established by clinical trials[4].One such fused pyrimidine core with nitrogen at ring junction is pyrido[1,2-a]pyrimidine. Pyrido[1,2-a]pyrimidine-4-one derivatives, were found to be aldols reductase (ALR2) inhibitor [5], human leukocyta elastase inhibitor [6], antibacterial agents [7], potential antiviral agents [8]. In light of the important biological properties of Pyrido[1,2-a]pyrimidines , the development of simple and convenient methodology for the synthesis of this structural motif represents an interesting area of research in synthetic organic and medicinal chemistry. Generally, the pyridopyrimidine ring is constructed by condensation based on the amidine fragment of 2- aminopyridine or its derivatives with various acylating and alkylating agents [9].Most of the reported methods involve the use high temperatures and pressure and use of acid catalysts with low yields and formation of significant amount of by products. Herein we report the convenient and versatile synthesis of 2H-pyrido[1,2-a]pyrimidine-2-one with high yields and purity by the reaction of 2-amno pyridine with the inexpensive reagent itaconic acid under conventional and microwave heating. PTSA(p-toluene sulfonic acid) was used as cylcizing agent, Since it makes the reaction process convenient, cost effective and environmentally benign[10]. 2. RESULTS AND DISCUSSION The title compound was synthesized by a convenient two step reaction, outlined in scheme -1. N N O R R R1 N NH 2 CH 2 -COOH C-COOH CH 2 NH N CH 2 -CH-COOH CH 2 -COOH 1 2 3 4 5 6 7 8 9 10 11 12 EtOH r.t + 2 3 1 4 R = H(3a),4Me(3b),6Me(3c) R1 =H,(4a) 6Me(4b),8Me(4c) Scheme - 1 The 2-amino pyridine was stirred with itaconic acid with alcohol in the first step to provide compound 3 (imino 1,2(H) pyridine itaconic acid) as white solid. Recrystallisation of the 2- imino 1,2(H) pyridine itaconic acid(3) yielded white crystals with 95%.Then imino 1,2(H) pyridine itaconic acid was heated with catalytic amounts of p-toluene sulfonic acid in alcohol to yield compound 2H- pyrido[1,2-a]pyrimidine-2-one(4) as white solid. Again