A Novel Approach to Pyrrolo[2,1-b]thiazoles

5-Aroyl-2-(dimethylamino)methylidene-2,3-dihydro-3-oxopyrrolo[2,1-b]thiazole-7-carboxylic acid esters, -7-carbonitriles and corresponding 7-hetaryl substituted derivatives were prepared. Thus, the substituted acetonitriles (XCH₂CN, where X = CO₂R, CN, hetaryl) were treated with mercaptoacetic acid yielding 2-(X-methylidene)thiazolidin-4-ones, which were N-alkylated with phenacyl bromides. Further formylation of the obtained compounds with excess of DMF•POCl₃ complex led to the above mentioned pyrrolo[2,1-b]thiazoles.