AbstractThe condensation of 1‐methyl‐pyrrolyl‐2‐carboxaldehyde with dimethyl methyl‐succinate in presence of sodium hydride gave predominantly the correspondingE‐half ester1a. However, the condensation of either 1‐methyl‐pyrrolyl‐ or furan‐2‐carboxaldehyde with dimethyl phenylsuccinate using either the potassium t‐butoxide or sodium hydride method produced a stereoisomeric mixture ofE‐ andZ‐half ‐esters. Cyclisation of theE‐half‐esters gave the corresponding benzofuran and indole derivatives2; whereas their hydrolysis produced theE‐dibasic acids6, which were convert