Synthesis and analgesic activity of 2-arylamino-3-aryl-5-methyl-6-(substituted) thieno [2,3-d] pyrimidin-4 (3H)-ones

A series of some new thieno [2,3-d] pyrimidin-4 (3H)-ones have been synthes ized by cyclocondensation of alkyl isothiourea ethers of sym-diarylthiourea s with 5-substituted 4-methylthiophene o-amino esters in dimethylformamide. All the synthesized compounds have been characterized with the help of spe ctral and elemental analysis. All the synthesized compounds were screened f or analgesic activity by tail flick method on albino rats and by writhing m ethod on albino mice. Compound Vh exhibited significant analgesic activity comparable to morphine in tail flick method and compounds Vb, Vd and Vg wer e found to possess analgesic activity comparable to that of aspirin by writ hing method in mice.