Tetrahydrofuran → 5-(1-Bromoethyl)-2-fluoropyridine

Temperature

-10 °C

A mixture of 6-fluoronicotinaldehyde (10.000 g, 80 mmol) in THF (300 mL) was chilled to −10° C. in a dry ice/acetone bath, then methylmagnesium bromide (3 M soln. in diethyl ether, Aldrich; 27.4 mL, 82 mmol) was added into the reaction mixture via addition funnel. After the addition, the ice bath was removed and the reaction mixture was allowed to stir under inert atmosphere 45 min. The mixture was chilled to −10° C. in a dry ice/acetone bath, then methanesulfonyl chloride (6.50 mL, 84 mmol) was slowly added into the reaction mixture via syringe. After the addition, the ice bath was removed and the reaction mixture was allowed to stir under an inert atmosphere for 2 h. The reaction mixture was quenched with water (100 mL) and diluted with chloroform (300 mL). The organic layer was extracted with chloroform (3×50 mL). The combined organic extracts were dried over sodium sulfate, filtered and concentrated in vacuo to give 5-(1-bromoethyl)-2-fluoropyridine (16.31 g, 80 mmol, 100% yield) as a tan oil. This material was carried into the next step of the synthesis immediately to prevent decomposition. 1H NMR (400 MHz, CDCl3) δ 8.25 (d, J=2.35 Hz, 1H) 7.93 (td, J=8.02, 2.54 Hz, 1H) 6.90-7.11 (m, 1H) 5.21 (q, J=6.85 Hz, 1H) 2.06 (d, J=7.04Hz, 3H). m/z (ESI, +ve ion) 205.9 (M+H)+.

1. additionAfter the addition
2. customthe ice bath was removed
3. temperatureThe mixture was chilled to −10° C. in a dry ice/acetone bath
4. additionAfter the addition
5. customthe ice bath was removed
6. stirringto stir under an inert atmosphere for 2 h
7. customThe reaction mixture was quenched with water (100 mL)
8. additiondiluted with chloroform (300 mL)
9. extractionThe organic layer was extracted with chloroform (3×50 mL)
10. dry with materialThe combined organic extracts were dried over sodium sulfate
11. filtrationfiltered
12. concentrationconcentrated in vacuo

ORD record

ord-80220657688144e99de03fe51e1b8fb0

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08772480B2