Allyl bromide → 1-tert-Butyl 4-ethyl 4-(prop-2-en-1-yl)piperidine-1,4-dicarboxylate

Temperature

-78 °C

A solution of 1-(1,1-dimethylethyl) 4-ethyl 1,4-piperidinedicarboxylate (25.0 g, 97 mmol) in tetrahydrofuran (100 mL) was added slowly to a stirred, cooled (−78° C.) solution of potassium hexamethyldisilazide (29.0 g, 145 mmol) in tetrahydrofuran (150 mL), maintaining the internal temperature below −65° C. The mixture was stirred at −78° C. for 30 minutes, then 3-bromopropene (12.6 mL, 145 mmol) was added dropwise over 10 minutes. The mixture was stirred at −78° C. for 1 hour, then saturated aqueous ammonium chloride (400 mL) and water (100 mL) were added and the mixture was warmed to room temperature. The mixture was extracted with ethyl acetate (3×400 mL) and the combined organic fractions were washed with aqueous citric acid (10%, 2×250 mL), saturated aqueous sodium hydrogen carbonate (400 mL) and brine (200 mL), dried (MgSO4) and the solvent was evaporated under reduced pressure to give the title compound (29.3 g, 100%). 1H NMR (400 MHz, CDCl3) δ 5.75-5.60 (1H, m), 5.10-5.00 (2H, m), 4.16 (2H, q, J 7 Hz), 3.92-3.78 (2H, m), 2.90 (2H, br t, J 14 Hz), 2.26 (2H, d, J 7 Hz), 2.08 (2H, br d, J 14 Hz), 1.45 (9H, s), 1.45-1.30 (2H, m), and 1.26 (3H, t, J 7 Hz).

1. temperaturemaintaining the internal temperature below −65° C
2. stirringThe mixture was stirred at −78° C. for 1 hour
3. temperaturethe mixture was warmed to room temperature
4. extractionThe mixture was extracted with ethyl acetate (3×400 mL)
5. washthe combined organic fractions were washed with aqueous citric acid (10%, 2×250 mL), saturated aqueous sodium hydrogen carbonate (400 mL) and brine (200 mL)
6. dry with materialdried (MgSO4)
7. customthe solvent was evaporated under reduced pressure

ORD record

ord-b5f11531d213493ab355c2a222cbdd91

Source dataset

uspto-grants-2007_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07253205B2