4H-Thieno[3,2-b]pyrrole-5-carboxylicacid, ethyl ester , its cas register number is 46193-76-4. It also can be called Ethyl 4H-thieno[3,2-b]pyrrole-5-carboxylate ; Ethyl 4H-thieno[2,3-d]pyrrole-5-carboxylate .