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.
title compounds, thieno[3,2-a]- and thieno[2,3-b]indolizine derivatives were obtained in fairly good yields. The cyclization modes observed in these transformation reactions were in accord with those expected by the molecular orbital calculations using some model compounds and by the stereochemical consideration of starting indolizines. The alkylations of 3-hydroxythieno[3,2-a]- and 3-hydroxythieno[2