Crushed KOH (0.0024 g, 0.0431 mmol) was added to 2-nitro-N-phenylbenzenesulfonamide (0.0100 g, 0.0359 mmol) in 0.2 mL DMF solution and the mixture was stirred for 30 min. 3,6-dibromo-9-(3-bromopropyl)-9H-carbazole (Example 35, 0.0240 g, 0.0538 mmol) in 0.3 mL DMF solution was added dropwise into the mixture and it was stirred at room temperature overnight. The crude reaction mixture was diluted with 20 mL EtOAc and washed with water 5×10 mL. The organic layer was dried over anhydrous Na2SO4 and evaporated to afford the crude product, which was subjected to silica gel chromatography using Hexanes/EtOAc to afford 0.0082 g white solid as impure product, purity 66.9% (impurity is starting Ns-aniline; used without additional purification), yield 35.5%.
