Synthesis of Benzo[1,2‐b:4,5‐b’]dithiophene and Benzocondensed Thiaheterocycles

Abstract A two‐step synthesis of benzo[1,2‐ b :4,5‐ b ’]dithiophene (BDT) was carried out starting from 3‐thiophene carbaldehyde as the sole thiophene precursor. This method involves the selective lithiation of the 2‐position of 3‐thiophenecarbaldehyde ethylene acetal, followed by the condensation with 3‐thiophenecarbaldehyde and subsequent dehydrative cycloaromatization of the dithienylmethanol intermediate to give BDT. This synthetic pathway was extended to other thiophene benzocondensed heterocycles.