In current clinical practice, two groups of agents like analgesic and antimicrobial drug are prescribed simultaneously. A POCl₃ catalyzed, efficient, one-step and solvent-free synthesis of novel thieno [2, 3-d] pyrimidin-4(3H)-one derivatives from 2-amino-4,5-substitutedthiophene-3-carbonitrile has been developed using various aliphatic acid  under conventional heating and microwave irradiation. The formation of compounds was confirmed using elemental analysis and spectroscopic techniques like IR, NMR (¹H) and mass spectroscopy. All synthesized compounds has been screened for their analgesic activity using Eddy´s hot plate method, antibacterial and antifungal activities against Escherichia coli (Gram –ve strain), Bacillus substilis (Gram +ve strain) Aspergillus niger and Candida albicans respectively. The compounds 2d, 2k and 2h showed good analgesic activity and compounds 2a, 2b, 2g and 2i showed moderate analgesic activity where as other compound possess significant analgesic activity compared with standard drug Tramadol, the compound were monitored for  in vitro antimicrobial testing. The results showed that some of the synthesized compounds exhibit weak, moderate and potent antimicrobial activity. It was observed that the compounds 2a, 2c, 2d, 2e, 2f, 2g, 2j and 2k showed good antimicrobial activity where as compounds 2b, 2i and 2j showed significant antimicrobial activity compared with standard drug Streptomycin and Amphotericin B respectively.

Keyword:   POCl₃, Thieno [2, 3-d] pyrimidin-4 (3H)-one, Analgesic activity, Antimicrobial activity , Eddy´s hot plate.