Fmoc-L-Aspartic acid-1-benzyl ester

117854-05-4

86060-83-5

Fmoc-Asp(OtBu)-OBn (1.604 g, 3.197 mmol) was used as a raw material and dissolved in 15 mL of freshly distilled dichloromethane (CH2Cl2). To this solution 15 mL of formic acid (HCOOH) was added and the reaction mixture was stirred at room temperature overnight. The reaction progress was monitored by thin layer chromatography (TLC) and after confirming the complete conversion of the feedstock, the volatiles were removed by distillation under reduced pressure. Subsequently, residual formic acid was removed by co-evaporation with dichloromethane to afford the white solid product Fmoc-Asp(OH)-OBn (1.310 g, 2.94 mmol, 92% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3) and 13C NMR (101 MHz, CDCl3).1H NMR data were as follows: δ 11.15 (s, 1H), 7.80 (d, J=7.5 Hz, 2H), 7.66 (d, J=7.4 Hz, 2H), 7.44 (t, J=7.4 Hz, 2H ), 7.36 (m, 7H), 6.16 (d, J=8.5Hz, 1H), 5.26 (s, 2H), 4.83 (dt, J=8.6,4.4Hz, 1H), 4.50 (dd, J=10.4,7.4Hz, 1H), 4.46-4.38 (m, 1H), 4.26 (t, J=7.1Hz, 1H), 4.26 (t, J=7.1Hz, 1H), and 3.18 (dd, J=17.4,4.6 Hz, 1H), 3.01 (dd, J=17.4,4.2 Hz, 1H).13C NMR data were as follows: δ 175.36, 170.34, 156.04, 143.53, 143.39, 141.02, 134.84, 128.34, 128.20, 127.94, 127.51, 126.87, 124.90, 119.76, 67.44, 67.21, 50.18, 46.79, 36.12.