Available online www.jocpr.com Journal of Chemical and Pharmaceutical Research, 2015, 7(6):181-191 Research Article ISSN : 0975-7384 CODEN(USA) : JCPRC5 181 Synthesis, molecular properties and evaluation of anthelmintic activity of new thiazolopyrimidine derivatives Shruthi N. 1 , Boja Poojary *1 , Vasantha Kumar 1 , Mahima Bhat 1 , Himanshu Joshi 2 and B. C. Revanasiddappa 2 1 Department of Chemistry, Mangalore University, Mangalagangothri, Karnataka, India 2 Department of Pharmacology, N.G.S.M. Institute of Pharmaceutical Sciences, Paneer, Deralakatte, Mangalore, Karnataka, India _____________________________________________________________________________________________ ABSTRACT In order to develop a better bioactive molecules with good efficacy, we synthesized a new series of Thiazolo [3,2-a] pyrimidine derivatives with good yield and studied their anthelmintic properties, structure- activity relationships (SARs). A new series of Thiazolo[3,2-a]pyrimidines have been synthesized through duff formylation, ‘One pot’ Biginelli reaction, cyclization followed by knoevenagel condensation and were characterized by IR, 1 H NMR, 13 C NMR, Mass spectra and elemental analysis. New molecules were screened for their in-vitro anthelmintic activity against Indian earthworm Pheretima posthuma and studied their physico-chemical properties. Effect of substitution at arylidene part on anthelmintic property was studied. Compounds 3j and 3s with electron withdrawing groups were found to be highly potent among the series and were also supported by ADME parameters. Keywords: Heterocycles, Cyclizations, Structure-activity relationships, Anthelmintic activity _____________________________________________________________________________________________ INTRODUCTION Helminthiasis is a macroparasitic disease found in humans due to parasitic worms, such as Nematodes or Cestodes which are exist in skin, liver, brain, lungs, lymph, eye, muscles and other tissues of the body [1]. The wide varieties of anthelmintics or anthelmintic drugs are available in market to expel such parasitic worms from the body by either stunning or killing them without causing any significant damage to the host cell. Especially, well known marketing pyrimidine derived drugs pyrantel and morantel, are commonly used as anthelmintic agents which has broad spectrum activity and high cure rates due to the sustainability of the periodic emergence of resistance. But some existing infectious diseases cannot be eliminated completely from human body by using presently available drugs [2]. Particularly, filariasis diagnosis is helpful for its cure only in its earlier stage. After the advancement of parasitic infection, it cannot be cured completely. It is unevenly distributed disease in low income countries which affected badly and showing the highest risk of morbidity day by day. Currently, the development of multicomponent reactions (MCRs) are integral part of numerous research efforts around the world which are involved in the drug development programs to achieve the synthetic targets in an expeditious manner. The Biginelli reaction is the one such reaction, which involves simple one pot three-component condensation of an aldehyde, β-ketoester, and urea or thiourea in the presence of a catalytic amount of acid to produce 3,4-dihydropyrimidin- 2-(1H)-ones (DHPMs) [3-4]. In order to bring about synthetic advancement, variations were introduced in different ways. The reaction was carried out by varying all the three building blocks i.e. biginelli scaffolds [5], catalyst [6-8], carried out asymmetric synthesis [9] and also rate enhancement reactions such as sonication [10] and microwave irradiation [11], which