32281-36-0

73540-75-7

32281-36-0

The general procedure for the synthesis of benzo[1,2-B:4,5-B']dithiophene-4,8-dione from N,N-diethyl-3-thiophenecarboxamide was as follows: 6.82 g (37.25 mmol, 1.0 eq.) of N,N-diethyl-3-thiophenecarboxamide was added to a 100 mL three-necked flask protected by nitrogen and three nitrogen substitutions were performed. Subsequently 30 mL of freshly distilled tetrahydrofuran was added. The reaction mixture was cooled in an ice-salt bath until the internal temperature was reduced to 0 °C, then 15.0 mL (37.25 mmol, 1.0 eq.) of 2.5 M n-butyllithium solution was slowly added dropwise for a controlled time of 20 min. After the dropwise addition, the reaction mixture was stirred at room temperature for 30 minutes. Subsequently, the reaction mixture was poured into 40 g of crushed ice and stirred overnight. On the following day, the product was collected by diafiltration and washed sequentially with water, methanol and petroleum ether. Finally, the resulting yellow powder was dried under vacuum to afford benzo[1,2-B:4,5-B']dithiophene-4,8-dione 3.50 g in 86.1% yield.