Abstract4,5‐Disubstituted 2‐mercaptoimidazoles react with chloroacetic acid to form S‐carboxy‐methyl derivatives, which readily cyclise to the corresponding 2,3‐dihydro‐imidazo[2,1‐b]‐thiazol‐3‐ones. Substituted amides of 2‐imidazolylthioacetic acids have now been obtained by the action of amines on the latter compounds.The 2‐arylidene and 2‐arylazo derivatives of 2,3‐dihydroimidazo[2,1‐b]thiazol‐3‐ones are prepared. The action of GRIGNARD reagents on the 2‐arylidene derivatives results in a