反应详情

A solution of alcohol 106 (678 mg, 2.36 mmol) and triphenylphosphine (746 mg, 2.84 mmol) in anhydrous CH2Cl2 (30 mL) was carefully treated with recrystallized N-bromosuccinimide (507 mg, 2.85 mmol) (water bath cooling), and the mixture was stirred at room temperature for 3 h. The resulting solution was concentrated, and then added to excess petroleum ether at the top of a silica gel column (25 g in petroleum ether), rinsing on with minimal extra CH2Cl2. Elution with petroleum ether firstly gave foreruns, and then further elution with 10-20% Et2O/pentane gave 2-(bromomethyl)-5-[3-fluoro-4-(trifluoromethoxy)phenyl]pyridine (107) (616 mg, 75%) as a white solid that was used directly in the next step; 1H NMR (CDCl3) δ 8.76 (dd, J=2.4, 0.6 Hz, 1H), 7.84 (dd, J=8.1, 2.4 Hz, 1H), 7.54 (dd, J=8.0, 0.6 Hz, 1H), 7.46-7.33 (m, 3H), 4.60 (s, 2H); HRESIMS calcd for C13H9BrE4NO m/z [M+H]+ 351.9778, 349.9798, found 351.9778, 349.9798.

1. concentrationThe resulting solution was concentrated
2. additionadded to excess petroleum ether at the top of a silica gel column (25 g in petroleum ether)
3. washrinsing on with minimal extra CH2Cl2
4. washElution with petroleum ether firstly gave foreruns
5. washfurther elution with 10-20% Et2O/pentane