Synthesis
Step 1. To a stirred solution of N-hydroxybutanediimide (1 g, 4 mmol) and CBZ-L-valine (459 mg, 4 mmol) in tetrahydrofuran (THF, 20 mL) was added N,N'-dicyclohexylcarbodiimide (DCC, 908 mg, 4.4 mmol) at 0° C. The reaction was carried out at room temperature. The reaction mixture was stirred at room temperature for 16 hours. After completion of the reaction, the mixture was filtered and the filtrate was concentrated to afford (S)-2,5-dioxopyrrolidin-1-yl 2-(((benzyloxy)carbonyl)amino)-3-methylbutanoate (yield: 90%).
References
[1] Chemical Communications, 2015, vol. 51, # 67, p. 13213 - 13216
[2] Organic and Biomolecular Chemistry, 2015, vol. 13, # 28, p. 7736 - 7749
[3] Patent: WO2015/95227, 2015, A2. Location in patent: Page/Page column 133
[4] Journal of Medicinal Chemistry, 2018, vol. 61, # 3, p. 989 - 1000
[5] Journal of the American Chemical Society, 2003, vol. 125, # 22, p. 6677 - 6686
