反应详情

To a solution of 1-tert-butyl 3-ethyl 3-methylpiperidine-1,3-dicarboxylate (15 g, 55.3 mmol) in THF (87 mL) and MeOH (87 mL) was added lithium hydroxide(2M in water) (172 mL, 345 mmol) at RT and stirred at same temperature for 15 h. The reaction mixture was cooled in an ice-bath, and adjusted to pH ˜4 by adding 1N HCl solution. The aqueous layer was extracted with ethylacetate (3×200 mL) and the combined organic extracts was washed with brine (20 mL), dried (Na2SO4), filtered and concentrated to give desired 1-(tert-butoxycarbonyl)-3-methylpiperidine-3-carboxylic acid (13.45 g, 54.2 mmol, 98% yield) as a white solid. This material was directly used for next step with out any further purification. Anal. Calcd. for C12H21NO4 m/z 243.3, found: 242.2 (M−H)+; 1H NMR (400 MHz, DMSO-d6) δ ppm 12.31 (s, 1 H) 3.68-3.52 (m, 1 H), 3.32-3.02 (m, 4 H), 1.89-1.82 (m, 1 H), 1.54-1.43 (m, 11 H) 1.06 (s, 3 H).

1. temperatureThe reaction mixture was cooled in an ice-bath
2. extractionThe aqueous layer was extracted with ethylacetate (3×200 mL)
3. washthe combined organic extracts was washed with brine (20 mL)
4. dry with materialdried (Na2SO4)
5. filtrationfiltered
6. concentrationconcentrated