Diethyl Ether → 1-Methyl-4-(tributylstannyl)-1H-pyrazole

Temperature

-78 °C

To a solution of 4-bromo-1-methylpyrazole (15 g, 38.5 mmol) in ether (150 mL) n-Butyllithium (2.5M in hexanes, 17 mL, 42.4 mmol) was added at −78° C. After the reaction solution was stirred at −78° C. for 30 minutes, tributyltin chloride (11.5 mL, 42.4 mmol) was added. It was stirred at −60° C. for 1 hour and warmed to room temperature, at which it was stirred for 1 more hour. Then, it was diluted with ethyl acetate (300 mL) and washed with water (200 mL) and brine. The organic layer was dried over anhydrous sodium sulfate and concentrated. The crude product was purified by flash column chromatography on silica gel with hexanes/ethyl acetate=10/1 as eluant to get 1-methyl-4-tributylstannylpyrazole as a white wax. 1H NMR (CDCl3, 300 MHz): δ7.42 (s, 1H), 7.23 (s, 1H), 3.93 (s, 3 H). 1.28-1.55 (m, 18 H), 0.91 (t, J=15 Hz, 9 H).

1. stirringIt was stirred at −60° C. for 1 hour
2. temperaturewarmed to room temperature, at which it
3. stirringwas stirred for 1 more hour
4. washwashed with water (200 mL) and brine
5. dry with materialThe organic layer was dried over anhydrous sodium sulfate
6. concentrationconcentrated
7. customThe crude product was purified by flash column chromatography on silica gel with hexanes/ethyl acetate=10/1 as eluant

ORD record

ord-1250c1e94d9b47249730199d2cb6e930

Source dataset

uspto-grants-2003_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06642237B1