Synthesis
The general procedure for the synthesis of (S)-2-hydroxy-3-methoxy-3,3-diphenylpropionic acid from 2-hydroxy-3-methoxy-3,3-diphenylpropionic acid was as follows: 500 mg (1.84 mmol) of (RS)-2-hydroxy-3-methoxy-3,3-diphenylpropionic acid was dissolved in 8 mL of 2-propanol, followed by addition of 135 mg (0.92 mmol) of (S)-(+)-1,2,3,4-tetrahydro-1-naphthylamine. The reaction mixture was stirred under heated reflux conditions for 1 hour, then cooled to room temperature and continued stirring for 2 hours. The precipitated crystals were collected by filtration, washed with 2-propanol and finally dried under reduced pressure. The same operations as in Example 1 were performed according to the solvents listed in Table 1.
References
[1] Patent: JP2017/128528, 2017, A. Location in patent: Paragraph 0005; 0041; 0042; 0045; 0046
[2] Patent: WO2012/17441, 2012, A1. Location in patent: Page/Page column 11-12
[3] Patent: CN104098462, 2017, B. Location in patent: Paragraph 0009; 0028; 0029; 0031
[4] Patent: JP5700378, 2015, B2. Location in patent: Paragraph 0071; 0072
[5] Patent: WO2013/57468, 2013, A1. Location in patent: Page/Page column 23-24
