Tris(1,1-dimethylethyl)phosphine → N-Phenyl-2-{4-[3-(dibenzothiophen-4-yl)-9H-carbazol-9-yl]phenyl}benzimidazole

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Reaction Conditions

Reaction Steps

In a 100-mL three-neck flask were put 0.36 g (1.0 mmol) of N-phenyl-2-(4-bromophenyl)benzimidazole and 0.36 g (1.0 mmol) of 3-(dibenzothiophen-4-yl)-9H-carbazole, and the air in the flask was replaced with nitrogen. To this mixture were added 10 mL of toluene, 0.10 mL of tri(tert-butyl)phosphine (a 10 wt % hexane solution), 0.15 g (4.3 mmol) of sodium tert-butoxide. This mixture was degassed while being stirred under reduced pressure. After this mixture was heated to 80° C., 5.0 mg (0.025 mmol) of bis(dibenzylideneacetone)palladium(0) was added thereto, and then the mixture was stirred at 80° C. for 3 hours. After the stirring, 14 mg (0.025 mmol) of bis(dibenzylideneacetone)palladium(0) was added to this mixture, and then it was further stirred at 110° C. for 7.5 hours. After the stirring, about 30 mL of toluene was added to the mixture, and then it was stirred at 80° C. This mixture was subjected to hot filtration with ethyl acetate through Celite (produced by Wako Pure Chemical Industries, Ltd., Catalog No. 531-16855), Florisil (produced by Wako Pure Chemical Industries, Ltd., Catalog No. 540-00135), and alumina. The obtained filtrate was concentrated to give a white solid. The obtained solid was dissolved in toluene. The mixture was purified by silica gel column chromatography (a developing solvent in which the hexane/ethyl acetate ratio was 4:1), and further recrystallized from toluene/hexane, so that 0.41 g of a white solid was obtained in 65% yield. The synthesis scheme of Step 2 is illustrated in (b-1).

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