Potassium Carbonate → Carbazole

Participants

Reaction Steps

A solution of 2,7-dibromo-9-octyl-9H-carbazole (220 mg, 0.5 mmol), 9H-carbazole-2-boronic acid pinacol ester (880 mg, 1.5 mmol) and benzyltriethylammonium chloride (50 mg) in a mixture of toluene (20 mL) and aqueous K2CO3 (2M, 8 mL) was degassed by three freeze-pump-thaw cycles. Pd(PPh3)4 (5 mg) was added under argon and degassed by three freeze-pump-thaw again. The mixture was refluxed for 24 h and the organic phase was separated and evaporated. The product was purified by column chromatography (hexane/THF, 4:2) and dried in vacuum. A 220 mg (71%) yield of trimer carbazole was obtained as a light brown powder. 1H NMR (THF-d8, 500 MHz): δ=10.33 (s, 2H), 8.15 (m, 4H), 8.07 (d, J=7.9, 2H), 7.82 (m, 4H), 7.6 (m, 4H), 7.43 (d, J=8.0, 2H), 7.34 (m, 2H), 7.15 (m, 2H), 4.56 (t, J=7.19, 2H), 1.99 (m, 2H), 1.29 (m, 10H), 0.83 (t, J=6.9, 3H). MALDI-TOF MS: m/z 609.33 (100%).

Provenance & Evidence