反应详情

A 6 N hydrochloric acid (400 mL) solution of tert-butyl (2S)-2-[(diphenylmethylene)amino]-3-[4-(trifluoromethoxy)phenyl]propanoate (41.2 g, 87.7 mmol) prepared in Reference Example 3 (3a) was heated under reflux for 3 hours and then cooled to room temperature. The reaction solution was concentrated under reduced pressure. The residue was washed with diethyl ether to give 23.8 g of a crude crystal (white powder, yield: 95%, optical purity: 84%). The crude crystalline solid (200 mg) was recrystallized from 1 N hydrochloric acid (1.5 mL) to give 120 mg of the title compound (colorless crystal, yield: 60%). No R-isomer was recognized in this compound by HPLC analysis according to the method described in Reference Example 3 (3c), and thereby it was confirmed that the optical purity was 99% or higher.

1. temperaturewas heated
2. temperatureunder reflux for 3 hours
3. concentrationThe reaction solution was concentrated under reduced pressure
4. washThe residue was washed with diethyl ether
5. customto give 23.8 g of a crude crystal (white powder, yield: 95%, optical purity: 84%)
6. customThe crude crystalline solid (200 mg) was recrystallized from 1 N hydrochloric acid (1.5 mL)