The alkaline treatment of ethyl l-cyano-2-(ethoxycarbonylmethylthio)indolizine-3-carboxylates and diethyl 2-(ethoxycarbonylmethylthio)indolizine-1,3-dicarboxylates afforded the corresponding diethyl 1-aminothieno[3,2-a]indolizine-2,4-dicarboxylates and diethyl 3-hydroxythieno[2,3-b]indolizine-2,9-dicarboxylates in good yields.