Sixteen new 2-benzylidene-7-methyl-3-oxo-5-(substituted phenyl)-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid methyl eaters (1a-4d) have been synthesized by reacting 1,2,3,4-tetrahydropyrimidine-2-thiones (1-4) with chloroacetic acid and appropriate benzaldehydes in a single step. Their structures have been proved by IR, H-1 NMR, mass spectra and elemental analysis. The compounds were tested for their anti-inflammatory activities. Test results revealed that compounds 1b, 1c, 4a and 4c exerted moderate anti-inflammatory activity at the 100 mg/kg dose level compared with indomethacin. (C) 1999 Elsevier Science S.A. All rights reserved.