Synthesis
Benzophenone imine (25.00 g, 137 mmol) was added in a single addition to a stirring solution of glycine methyl ester hydrochloride (17.49 g, 139 mmol) in anhydrous dichloromethane (150 mL) under nitrogen atmosphere and at room temperature. The reaction mixture was stirred continuously for 24 h, during which ammonium chloride precipitation was observed to be generated. Upon completion of the reaction, water (20 mL) was added for layering. The organic layer was washed sequentially with saturated sodium carbonate solution (2 x 20 mL) and brine (20 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated using a rotary evaporator to give about 35 g of a thick light brown slurry (99% purity) in near 100% yield. The product did not require further purification and could be used directly in the subsequent reaction.
References
[1] Bioorganic and Medicinal Chemistry Letters, 2001, vol. 11, # 15, p. 1975 - 1979
[2] Patent: WO2004/5293, 2004, A2. Location in patent: Page 69-70
[3] Patent: WO2006/23630, 2006, A2. Location in patent: Page/Page column 39-40; 65
[4] Chemistry - A European Journal, 2012, vol. 18, # 12, p. 3773 - 3779
[5] Organic Process Research and Development, 2018, vol. 22, # 10, p. 1458 - 1460
