Boc-Asp-OtBu

80963-08-2

34582-32-6

General procedure for the synthesis of N-tert-butoxycarbonyl-L-aspartic acid 1-tert-butyl ester from (S)-2-(BOC-amino) succinic acid (4-benzyl) ester (1-tert-butyl): (S)-2-(BOC-amino) succinic acid (4-benzyl) ester (1-tert-butyl) ester (1.04 g, 2.74 mmol) was reacted with 10% Pd/C (0.2 g) in a The mixture in anhydrous ethanol (20 mL) was placed under hydrogen atmosphere (50 psi) and the reaction was shaken for 3 hours. Upon completion of the reaction, the mixture was filtered and the filtrate was concentrated under vacuum to give a white crystalline solid N-tert-butyl N-tert-butoxycarbonyl-L-aspartate 1- tert-butyl ester (0.79 g, 100%). The product has a melting point of 97-99 °C (literature value 1: 97-98 °C; literature value 2: 98-100 °C); specific rotation [α]24D = -16.9 (c = 1.0, EtOH) and [α]23D = -23.6 (c = 1.5, MeOH) (literature 2: [α]22D = +19.6 (c = 1.0, CHCl3); literature 3: [α] 25D = -7.4 (c = 2.0, MeOH)).1H NMR (200 MHz, CDCl3) δ 10.33 (br s, 1H), 5.48 (d, 1H, J = 8.0 Hz), 4.45 (t, 1H, J = 4.0 Hz), 3.02 (dd, 1H, J1 = 17.0 Hz, J2 = 4.0 Hz), 2.81 ( dd, 1H, J1 = 11 Hz, J2 = 4.6 Hz), 1.45 (br s, 18H); 13C NMR (50 MHz, CDCl3) δ 175.8, 169.9, 155.7, 82.4, 80.2, 50.5, 36.8, 28.3, 27.9; High-resolution mass spectrometry (HRMS) calculations C13H23NaNO6(M + Na)+: 312.1423, measured value: 312.1420. references: 1. C. C. Yang, R. B. Merrifield. Journal of Organic Chemistry 1976, 41, 1032-1041; 2. Robert M. Adlington, Jack E. Baldwin, David Catterick, Gareth J. Pareth, J. Pritchard. J. Chem. Soc., Perkin Trans. 1, 1999, 855-866.