The condensation of ethyl 2-cyano-3,3-dimethylthioacrylate (I) with S-methylisothiourea (II) in refluxing ethanol yielded pyrimidinone (V). Alternatively, the intermediate pyrimidinone (V) was obtained by condensation of 2-cyano-3,3-dimethylthioacrylamide (III) with anhydride (IV). Subsequent chlorination of (V) with refluxing phosphoryl chloride provided the title chloropyrimidine.