反应详情

温度

40 °C

Commercially available copper(I)bromide (7.17 g, 50 mmol) and anhydrous lithium bromide (8.68 g, 100 mmol) were added to anhydrous THF (100 mL). Vigorous shaking gave a dark greenish solution. 11.5 mL (5.75 mmol) of this solution was added to a mixture of 1,4-dibromobutane (74.8 g, 346 mmol) in THF (90 mL). The mixture was warmed to 40°C, after which a solution of 2,4-dimethoxyphenylmagnesium bromide (115 mmol) in THF (100 mL), prepared by standard methods, was added over 45 min. The temperature was never more than 50° C. After the addition, the mixture was stirred for an additional 1 h at 50° C. The reaction mixture was allowed to reach 30° C. after which it was poured into ice water (200 mL). Effective stirring for 10 min gave a deep blue color. The mixture was extracted with diethyl ether (2×250 mL), dried (MgSO4) and evaporated. The excess of 1,4-dibromobutane was distilled off, and the residue was filtered through a short column of silica gel (hexane-EtOAC, 95:5). Evaporation gave the title compound as a colorless liquid (23.0 g): 1H NMR (CDCl3 -d) 7.00 (d, J=8.0 Hz, 1 H), 6.44-6.39 (m, 2 H), 3.79 (s, 6 H), 3.42 (t, J=6.9 Hz, 2 H), 2.56 (t, J=7.5 Hz, 2 H), 1.90-1.83 (m, 2 H), 1.73-1.62 (m, 2 H); 13C NMR (CDCl3 -d) 159.13, 158.24, 129.90, 122.56, 103.74, 98.44, 55.30, 55.22, 33.87, 32.47, 28.56 (two overlapping carbon); MS (EI, 70 eV): m/z (rel.int.) 274/272 (M+, 100/96), 151 (54), 121 (43), 91 (14).

1. customgave a dark greenish solution
2. additionwas added over 45 min
3. customwas never more than 50° C
4. additionAfter the addition
5. stirringthe mixture was stirred for an additional 1 h at 50° C
6. customto reach 30° C.
7. stirringEffective stirring for 10 min
8. customgave a deep blue color
9. extractionThe mixture was extracted with diethyl ether (2×250 mL)
10. dry with materialdried (MgSO4)
11. customevaporated
12. distillationThe excess of 1,4-dibromobutane was distilled off
13. filtrationthe residue was filtered through a short column of silica gel (hexane-EtOAC, 95:5)
14. customEvaporation