2,2′-(1-(tert-Butoxycarbonyl)pyrrolidine-3,4-diyl)diacetic Acid

as a white solid. Mp: 162–163 °C, % purity: 94.09% (HPLC);

¹H NMR (DMSO-d₆, 400 MHz) δ: 1.38 (s, 9H), 2.10–2.18 (m, 2H), 2.28–2.32 (m, 2H), 2.49–2.50 (m, 2H, merged with DMSO peak), 2.97–3.03 (m, 2H), 3.33–3.40 (m, 2H), 12.23 (bs, 2H); ¹H NMR (CD₃OD, 400 MHz) δ: 1.46 (s, 9H), 2.26 (ddd, J₁ = 2.8 Hz, J₂ = 9.2 Hz, J₃ = 16.0 Hz, 2H), 2.43 (dd, J₁ = 5.2 Hz, J₂ = 16.0 Hz, 2H), 2.69 (m, 2H), 3.16 (dd, J₁ = 5.2 Hz, J₂ = 10.8 Hz, 2H), 3.49–3.54 (m, 2H);

¹³C NMR (DMSO-d₆, 100 MHz) δ: 28.49, 32.97, 36.49, 37.31, 50.10, 50.20, 78.67, 154.05, 173.96;

IR (KBr): ν = 871, 933, 1143, 1166, 1292, 1411, 1689, 1708, 2881, 2929, 2980, 3001 cm^–1;

TOFMS: [C₁₃H₂₁NO₆ – H⁺]: calculated 286.1296, found 286.1031(100%).

HPLC conditions were as follows for compound ; Agilent 1100 series, column: YMC J’SPHERE C18 (150 mm X 4.6 mm) 4µm with mobile phases A (0.05% TFA in water) and B (acetonitrile). Detection was at 210 nm, flow was set at 1.0 mL/min, and the temperature was 30 °C (Run time: 45 min). Gradient: 0 min, A = 90%, B = 10%; 5.0 min, A = 90%, B = 10%; 25 min, A = 0%, B = 100%; 30 min, A = 0%, B = 100%, 35 min, A = 90%, B = 10%; 45 min, A = 90%, B = 10%.

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