Carbon tetrabromide → Methyl 8-bromooctanoate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of crude methyl-8-hydroxy-octanoate (7, 1.24 g, 7.13 mmol, 1.0 equiv.) in CH2Cl2 (15 mL, 0.48 M) at 0° C. was treated successively with CBr4 (3.07 g, 9.27 mmol, 1.3 equiv.) and PPh3 (2.61 g, 9.98 mmol, 1.4 equiv.) and the reaction mixture was stirred at 4° C. for 10 h. The reaction mixture was then concentrated under reduced pressure and washed repeatedly with Et2O (8×10 mL washes). The Et2O washes were combined and concentrated under reduced pressure. Chromatography (SiO2, 5 cm×15 cm, hexanes) afforded 8 as a clear, colorless oil (1.25 g, 1.69 g theoretical, 74.0%): 1H NMR (CDCl3, 250 MHz) δ 3.64 (s, 3H, C(O)OCH3), 3.38 (t, 2H, J=6.8 Hz, CH2Br), 2.29 (t, 2H, J=7.4 Hz CH2C(O)OCH3), 1.83 (p, 2H, CH2CH2Br), 1.63 (m, 2H, CH2CH2C(O)OCH3) 1.47-1.28 (m, 6H, alkyl protons).

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