Peracetic Acid → 5-(1-Bromoethyl)-2-fluoropyridine

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Thionyl bromide (11.60 mL, 149 mmol) was added (dropwise over 15 min; gas evolution) to a solution of 1-(6-fluoropyridin-3-yl)ethanol (10.55 g, 74.7 mmol) in DCM (300 mL) at 25° C., and the resulting orange solution was stirred at 25° C. for 3 h. Excess SOBr2 was then carefully quenched with water (150 mL) at 0° C. with vigorous stirring, and 5.0N aqueous NaOH (100 mL) was then carefully added at 0° C. (over about 10 min) to neutralize HBr and SO2. (Yellow mixture results; final pH about 9; adjust with saturated aqueous NaHCO3,to a pH of about 9 as necessary.) The resulting mixture was vigorously stirred at 0° C. for 5 min to ensure complete quench of acidic species, and the resulting mixture was then partitioned between DCM (200 mL) and half saturated aqueous NaHCO3 to a pH of about 9 (600 mL). The organic layer was separated, and the aqueous layer was extracted with DCM (300 mL). The combined organic extracts were sequentially washed with saturated aqueous NaHCO3 (500 mL) and brine (500 mL), dried over sodium sulfate, filtered, and concentrated in vacuo to provide 5-(1-bromoethyl)-2-fluoropyridine (14.58 g, 96% yield) as a yellow oil (71% LCAP; m/z (ESI, +ve) 204.0 (M+H)+), which was used directly in Step 3.

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