2,6-Dimethylpyrrolo[2,1-b)]thiazole, 8, undergoes electrophilic substitution with dimethyl acetylenedicarboxylate to form the cis- and trans-5-dicarbomethoxyvinyl derivatives of 8. With tetracyanoethylene as electrophile, 5- and 7-tricyanovinyl derivatives of 8 are formed. Butyllithium metalates 8 in position 3, whereas 3-methyl-6-phenylpyrrolo(2,1-b]thiazole, 18, is metalated in position 2. Reaction