Bromide ion → 3-(2-bromoethyl)Benzofuran

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반응 단계

Triphenylphosphane dibromide (5.52 g, 14.41 mmol) was suspended in abs. acetonitrile (15 ml) under argon, the suspension was brought to 19° C. in a water batch and 2-(benzofuran-3-yl)ethanol (2.11 g, 13.1 mmol), dissolved in abs. acetonitrile (7 ml) was added in the course of 15 min. During the addition the temperature of the reaction mixture was kept between 19 and 21° C. The mixture was then left to stand for 12 h without further cooling. The triphenylphosphane which had precipitated out during this period of time was removed from the reaction mixture by filtration. The filtrate obtained was concentrated. For complete removal of the phosphane, the residue obtained was taken up in cyclohexane (20 ml) and the mixture was filtered over a layer of silica gel (15 g) about 3 cm thick. The silica gel was washed with cyclohexane (5×20 ml). The solution obtained in t his way, which contains the desired bromide in a pure form, was concentrated on a rotary evaporator. This was isolated in a yield of 2.47 g (87%) as a yellowish oil.

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