反应详情

To a solution of 3-methyl 1-(phenylmethyl) (3S)-1,3-pyrazolidinedicarboxylate (2.77 g, 10.5 mmol) in THF (20 mL) at 0° C. was added a portion of LiOH monohydrate. The mixture was warmed up to rt and stirred for 2 hours. TLC showed that the starting material was consumed completely. THF was distilled off, and the mixture was cooled to 0° C. Citric acid (4.8 g, 25.2 mmol) in water (20 mL) was then added dropwise. The aqueous mixture was extracted with DCM (8×20 mL), the combined organic phases were dried (Na2SO4), filtered and concentrated to provide (3S)-1-{[(phenylmethyl)oxy]carbonyl}-3-pyrazolidinecarboxylic acid as yellowish solid (1.8 g, 83%). 1H NMR (300 MHz, DMSO-D6) δ 7.43-7.29 (m, 5H), 5.07 (s, 2H), 3.76-3.71 (m, 1H), 3.52-3.37 (m, 2H), 2.25-2.06 (m, 2H).

1. customwas consumed completely
2. distillationTHF was distilled off
3. temperaturethe mixture was cooled to 0° C
4. extractionThe aqueous mixture was extracted with DCM (8×20 mL)
5. dry with materialthe combined organic phases were dried (Na2SO4)
6. filtrationfiltered
7. concentrationconcentrated