Ammonia → 2-(4'-Ethyl-2,3-difluorobiphenyl-4-yl)-5-methylselenophene

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Reaction Steps

3.7 ml (21.7 mmol) of TMP are initially introduced at −15° C. in 10 ml of diethyl ether, and 13.0 ml (20.7 mmol, 15% soln. in hexane) of n-BuLi are metered in. After 30 min, a solution of 6.8 g (19.6 mmol) of 2-(4′-ethyl-2,3-difluorobiphenyl-4-yl)selenophene in 50 ml of diethyl ether is added. When the addition is complete, the batch is warmed to RT and stirred for 90 min. The solution is cooled to −70° C., and 6.0 ml (96.4 mmol) of methyl iodide are added. The reaction mixture is warmed to RT and stirred for 20 h. Sat. ammonium chloride soln. and conc. ammonia soln. are added successively, and the mixture is stirred vigorously for a few minutes. The organic phase is separated off, and the aqueous phase is extracted with MTBE. The combined organic phases are washed successively with water, 2 N hydrochloric acid and sat. sodium chloride soln. The solution is dried using sodium sulfate and concentrated to dryness. The crude product is purified by column chromatography (SiO2, n-heptane:toluene=9:1). The further purification is carried out by recrystallisation from ethanol and n-heptane. 2-(4′-Ethyl-2,3-difluorobiphenyl-4-yl)-5-methylselenophene is obtained as a solid having an m.p. of 92° C.

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