To a 100 mL flask under nitrogen protection was added 3,6-bis(5-bromo-2-thienyl)-2,5-bis(2-ethylhexyl)-2,5-dihydropyrrolo[3,4-C]pyrrole-1,4-dione (3.70 g, 5.4 mmol), bis(pinacolato)diboron (3.00 g, 11.8 mmol), potassium acetate (2.59 g, 26.4 mmol), [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride dichloromethane adduct (0.09 g, 0.1 mmol), 1,1'-bis(diphenylphosphino)ferrocene (0.06 g, 0.1 mmol) and anhydrous 1,4-dioxane (300 mL). The mixture was heated with stirring at 120 °C for 15 hours. After completion of the reaction, the reaction solution was filtered through diatomaceous earth and the filtrate was concentrated by rotary evaporator. Chloroform (200 mL) was added to the residue and heated with stirring at 80 °C, followed by the addition of acetonitrile (400 mL), and this operation was repeated 5 times. The mixture was stirred and cooled to room temperature and stirring was continued for 1 hour. The solid product was collected by filtration, washed twice with acetonitrile (100 mL) and dried under reduced pressure to afford 2,5-bis(2-ethylhexyl)-3,6-bis(5-boronic acid pinacol ester thienyl)- pyrrolo[pyrrolidin]dione (Compound 14) in a yield of 2.25 g (0.24 mmol) in 53.4%.