Synthesis
General procedure for the synthesis of (S)-3-dimethylamino-3-phenylpropanol from formaldehyde and (S)-3-amino-3-phenylpropanol: (S)-3-Amino-3-phenylpropanol (1.5 kg) prepared as above was dissolved in 1.6 kg (88%, 30 mol) of formic acid, followed by addition of 2.8 kg (37%, 35 mol) of formaldehyde solution. The reaction mixture was heated to reflux for 8 hours. Upon completion of the reaction, a burst treatment was performed followed by concentration of the reaction solution under reduced pressure. To the concentrated solution, 2 L of 7K solution was added and the pH was adjusted with 10% aqueous sodium hydroxide solution to 12. Extraction was carried out with ethyl acetate (3 L × 4) and the organic phases were combined. The organic phase was washed twice with 6 L of saturated saline, respectively. The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure to give 1.65 kg of (S)-3-dimethylamino-3-phenylpropanol, which was analyzed by high-performance liquid chromatography (HPLC) with a purity of 97.36% and a yield of 93.02%. Ethyl acetate can be recovered for recycling.
References
[1] Patent: CN106883133, 2017, A. Location in patent: Paragraph 0048-0049; 0095; 0097
[2] Tetrahedron Asymmetry, 2007, vol. 18, # 17, p. 2099 - 2103
[3] Tetrahedron Asymmetry, 2006, vol. 17, # 5, p. 860 - 866
[4] European Journal of Organic Chemistry, 2014, vol. 2014, # 12, p. 2543 - 2548
[5] Tetrahedron, 2009, vol. 65, # 12, p. 2605 - 2609
