136027-17-3

(3) 120 mL of concentrated ammonia (3.12 moles) was added to the reaction flask, cooled to 5 ± 2 °C and stirred. Subsequently, 150 ml of tetrahydrofuran solution containing 150.7 g of compound 4 (0.543 mol) was slowly added dropwise for a controlled time of 0.5 to 1 hour. After the dropwise addition, the reaction temperature was adjusted to 10±2°C and the reaction was continued for 2 hours. After completion of the reaction, the tetrahydrofuran was removed by distillation under reduced pressure. The residue was filtered and the filter cake was dissolved in 224 mL of methanol and subjected to pulping treatment at a controlled temperature of 20°C for 2 hours. It was filtered again and dried to give 133.9 g of white solid, benzyloxycarbonylaminoethylsulfonamide (compound 5) in 95.6% yield.

[1] Patent: CN106008283, 2016, A. Location in patent: Paragraph 0028; 0029; 0030
[2] Patent: EP2484678, 2012, A1. Location in patent: Page/Page column 14
[3] Patent: US2012/208833, 2012, A1. Location in patent: Page/Page column 10
[4] Amino Acids, 2012, vol. 43, # 1, p. 423 - 429
[5] Journal of the American Chemical Society, 2006, vol. 128, # 6, p. 1995 - 2004