Pyrrolo[2,1-b]thiazol-3(2H)-ones as Precursors of N-Alkyl-2-(1H-pyrrol-2-ylthio)acetamides and N-Alkyl-2-(1H-pyrrol-2-ylthio)propanamide

6-Aryl-2,3-dihydro-3-oxopyrrolo[2,1-b]thiazole-7-carboxylic acids ethyl esters were prepared by refluxing 2-[3-(2-aryl-2-oxoethyl)-4-oxo-2-thiazolidinylidene]acetic acid ethyl esters in POCl₃. An amination of the obtained pyrrolo[2,1-b]thiazole derivatives with primary aliphatic amines was found to yield N-alkyl-2-[(4-aryl-3-ethoxycarbonyl-2-pyrrolyl)thio]acetamides and -propanamides.