Chlorotrimethylsilane → Tert-butyl 4-(2-bromoacetyl)-3-methylpiperidine-1-carboxylate

関与物質

反応条件

反応手順

To a cooled (−78° C.) solution of LDA (5.69 mL, 11.4 mmol) in THF (100 mL) was added dropwise over 40 minutes a solution of tert-butyl 4-acetyl-3-methylpiperidine-1-carboxylate (2.29 g, 9.48 mmol) in THF (40 mL). After an additional 25 minutes, chlorotrimethylsilane (2.41 mL, 18.9 mmol) was added dropwise over 20 minutes. After stirring for 1 hour the reaction was poured into 600 mL saturated sodium bicarbonate and extracted with ether (2×400 mL). The combined ether layers were washed with brine, dried, filtered, and concentrated to afford crude TMS-enol ether, which was then redissolved in 500 mL THF and cooled to 0° C. and treated with sodium bicarbonate (1.20 g, 14.2 mmol), followed by NBS (1.69 g, 9.48 mmol). The reaction was allowed to warm to ambient temperature while stirring for 90 minutes at which point it was poured into 400 mL of saturated sodium bicarbonate solution and extracted with Et2O and the combined organic layers were washed with saturated NaHCO3, brine, dried, and concentrated to give the title compound (3.35 g, 110% yield) as an orange oil.

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