91229-86-6

The general procedure for the synthesis of tert-butyl (S)-5-bromo-2-((tert-butoxycarbonyl)amino)-5-hydroxypentanoate from (S)-2-((tert-butoxycarbonyl)amino)-5-hydroxypentanoic acid is as follows: 1. tert-Butyl (S)-2-((tert-butoxycarbonyl)amino)-5-hydroxypentanoate (210.2 mg) was dissolved in dichloromethane (7.3 mL) and cooled to 0°C. 2. Carbon tetrabromide (1.5 eq.) and triphenylphosphine (2.0 eq.) were added sequentially and the reaction mixture was stirred at 0 °C for 20 min. 3. Upon completion of the reaction, the reaction was terminated with hexane/ethyl acetate (2:1, v/v). 4. The reaction mixture was purified by silica gel column chromatography (eluent: hexane/ethyl acetate, 2:1, v/v) to afford 254.6 mg (S)-tert-butyl 5-bromo-2-((tert-butoxycarbonyl)amino)pentanoate in 100% yield as a colorless oil.

[1] Patent: EP2952504, 2015, A1. Location in patent: Paragraph 0151-0152
[2] European Journal of Organic Chemistry, 2004, # 21, p. 4391 - 4396
[3] Journal of Organic Chemistry, 1984, vol. 49, # 19, p. 3527 - 3534
[4] Chemistry Letters, 1996, # 8, p. 621 - 622