Triphenylphosphine → 2-Bromo-5-bromomethylpyridine

Participants

Reaction Steps

A solution of (6-bromo-3-pyridinyl)methanol (50) (2.503 g, 13.3 mmol) and triphenylphosphine (4.026 g, 15.4 mmol) in anhydrous CH2Cl2 (100 mL) was carefully treated with recrystallized N-bromosuccinimide (2.732 g, 15.4 mmol) (water bath cooling), and the mixture was stirred at room temperature for 3.5 h. The resulting solution was concentrated, and then added to excess petroleum ether at the top of a silica gel column (100 g in petroleum ether), rinsing on with minimal extra CH2Cl2. Elution with petroleum ether firstly gave foreruns, and then further elution with 15-25% Et2O/pentane gave pure 2-bromo-5-(bromomethyl)pyridine (51) (Schubert et al., 1999) (3.045 g, 91%) as a lachrymatory white solid that was used directly in the next step; 1H NMR (CDCl3) δ 8.38 (d, J=2.5 Hz, 1H), 7.59 (dd, J=8.2, 2.6 Hz, 1H), 7.48 (d, J=8.2 Hz, 1H), 4.42 (s, 2H).

Provenance & Evidence