A simple and efficient one-pot synthesis of 1-[3-alkyl-4-methyl-2-thioxo-2,3-dihydrothiazole-5-yl]-ethanones from the reaction of primary alkylamines and carbon disulfide in the presence of 3-chloro acetylacetone is described. This protocol has several advantages such as lack of need for a solvent and catalyst, high yields, mild conditions and short reaction times.