Polycondensed heterocycles. II. A new preparative route to 11‐Oxo‐5 H ,11 H ‐pyrrolo[2,1‐ c ][1,4]benzothiazepine

6‐Methylthio‐10‐oxo‐5 H ,10 H ‐pyrrolo[1,2‐ b ]isoquinoline 11 was isolated in an attempted synthesis of 11‐oxo‐5 H ,11 H ‐pyrrolo[2,1‐ c ][1,4]benzothiazepine 1 from 1‐(2‐methylthiobenzyl)pyrrole‐2‐carboxylic acid chloride 9 , obtained using as starting material o ‐methylthiobenzyl bromide 3 and passing through 1‐(2‐methylthiobenzyl)pyrrole‐2‐carbonitrile 5 , by cyclization with aluminum chloride. However the successful demethylation with sodium in dimethylacetamide of 1‐(2‐methylthiobenzyl)pyrrole‐2‐carboxyamide 12 , formed by hydrolysis of nitrile 5 , allowed us to prepare by another way the corresponding thiol 13 and consequently the 1‐(2‐mercaptobenzyl)pyrrole‐2‐carboxylic acid 14 , which when subjected to intramolecular ring closure by CDI in place of DCC gave 1 in higher yield, 69% instead of 43%. Finally, the direct cyanation of 1‐(2‐ethoxycarbonylthiobenzyl)pyrrole 16 , prepared utilizing the 1‐(2‐mercaptobenzyl)pyrrole 15 obtained by demethylation of the corresponding thioanisol 4 which was carried out as above, afforded the unexpected 1‐(2‐ethylthio‐benzyl)pyrrole‐2‐carbonitrile 17 .