Sodium borohydride → 2-Fluoro-5-(1-(4-(methylthio)phenyl)ethyl)pyridine

Participants

Reaction Steps

2-Fluoro-5-(1-(4-(methylthio)phenyl)vinyl)pyridine (992 mg, 4.04 mmol) was dissolved in THF (12 mL) and water (4 mL) and the flask was cooled in an ice water bath under nitrogen. Then, ruthenium trichloride hydrate (212.4 mg, 0.9422 mmol) was added, and then sodium borohydride (393 mg, 10.4 mmol) was added portionwise over about 5 min. More THF (2 mL) was added, and the reaction was warmed to room temperature and stirred. After 2 hours and 15 minutes, more RuCl3*H2O (214 mg, 0.951 mmol) was added and the flask was again cooled in an ice water bath. Then, more sodium borohydride (384 mg, 10.2 mmol) was added, and the reaction was warmed to room temperature. The stirring was continued. Gas evolution was observed. After 50 min, more sodium borohydride (139 mg, 3.67 mmol) was added, and stirring was continued for 1 h. The reaction was diluted with water (20 mL) and DCM (30 mL). The suspension was filtered through a Celite® (diatomaceous earth) pad, which was washed repeatedly with DCM. The biphasic mixture was treated with saturated sodium bicarbonate (50 mL), and the layers were separated. The aqueous phase was extracted with DCM, and all the organic phases were combined, dried over sodium sulfate, filtered, concentrated, and purified on a silica gel filter (150 mL fritted funnel with about 2 inches of silica gel; DCM) to give 2-fluoro-5-(1-(4-(methylthio)phenyl)ethyl)pyridine (875 mg). 1H NMR (CDCl3, 400 MHz) δ 8.10 (d, J=1.96 Hz, 1H), 7.56 (td, J=8.07 Hz, 2.64 Hz, 1H), 7.24-7.19 (m, 2H), 7.15-7.09 (m, 2H), 6.84 (dd, J=8.41 Hz, 2.93 Hz, 1H), 4.15 (q, J=7.24 Hz, 1H), 2.47 (s, 3H), 1.64 (d, J=7.24 Hz, 3H). m/z (ESI, pos. ion) 248 (M+H)+.

Provenance & Evidence