The general procedure for the synthesis of 1,3-dibromo-5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione using 5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione as a starting material was as follows: 5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6( 5H)-dione (0.27 g, 1.01 mmol) was dissolved in a solvent mixture of concentrated sulfuric acid (1.6 mL) and trifluoroacetic acid (3.4 mL). Subsequently, N-bromosuccinimide (NBS, 0.543 g, 3.05 mmol) was added all at once and the reaction mixture was stirred at room temperature overnight. After completion of the reaction, the resulting solution was diluted with water (100 mL) and extracted with dichloromethane. The organic phase was sequentially washed with potassium hydroxide (KOH) solution and dried over anhydrous magnesium sulfate, followed by evaporation of the solvent to give the crude product, which appeared as orange crystals. Purification by silica gel column chromatography using hexane/chloroform (3:2, v/v) as eluent finally afforded 1,3-dibromo-5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (0.34 g, 79% yield) as a pink solid. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 3.49 (d, J = 7.3 Hz, 2H), 1.81-1.76 (m, 1H), 1.35-1.27 (m, 8H), 0.93-0.88 (t, 6H). 13C NMR (100 MHz, CDCl3): δ 160.46, 134.46, 134.46. 112.65, 42.26, 37.80, 30.13, 28.13, 23.43, 22.54, 13.66, 9.95. The melting point ranges from 110.5 to 112 °C. MALDI-TOF mass spectrometry analysis showed that the molecular ions peaks [M + H]+ had a m/z of 424.5344, which is consistent with the theoretically calculated value C14H17Br2NO2S which is consistent with the theoretically calculated value of C14H17Br2NO2S.
![5-(2-Ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione](/CAS/20150408/GIF/1231160-82-9.gif)
![1,3-BibroMo-5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione](/CAS/GIF/1231160-83-0.gif)