Dithieno[2,3-b:2',3'-d]thiophene

502764-53-6

3593-75-7

General procedure for the synthesis of dithieno[3,2-b:2',3'-d]thiophene-2,6-dicarboxylic acid from dithieno[3,2-b:2',3'-d]thiophene: 113.0 g (0.397 mol) of the compound denoted by Eqs. 3-d, 24.0 g (0.378 mol) of copper powder (prepared from Reaction Eq. 18) and 791 mL of quinoline were added to a 1 L round bottomed flask and heated to reflux. Stirring was continued at 230 °C until complete release of carbon dioxide gas. After the reaction mixture was cooled to room temperature, the product was purified by column chromatography using hexane as eluent to finally obtain 58.8 g (75.4% yield) of the compound represented by formula 3-e.