Synthesis
GENERAL STEPS: 2.3 g of Na2CO3 was dissolved in 34 mL of water and chloroformic acid-9-fluorenylmethyl ester and (S)-2-amino-2-cyclopropylacetic acid were added with stirring. The reaction mixture was stirred at room temperature. After completion of the reaction, the product was characterized by FT-IR and NMR.FT-IR (pure): 2669, 2335, 2159, 2106, 1785, 1689, 1550, 1489, 1463, 1433, 1369, 1296, 1253, 1172, 1128, 1001 cm^-1.^1H NMR ( CDCl3, 600 MHz): δ = 7.76 (d, 2H, J = 7.2 Hz), 7.60-7.59 (m, 2H), 7.41-7.39 (m, 2H), 7.32-7.30 (m, 2H), 5.36 (d, 1H, J = 6 Hz), 4.45-4.39 (m, 2H), 4.24-4.21 (m, 1H ), 3.83-3.81 (m, 1H), 1.14-1.13 (m, 1H), 0.65-0.46 (m, 5H) ppm. ^13C NMR (CDCl3, 150 MHz): δ = 176.6, 156.2, 143.9, 143.8, 141.4, 127.9, 127.2, 125.2, 125.1 , 120.1, 67.3, 57.4, 47.3, 13.9, 3.4 ppm. HRMS (ESI): m/z [M + Na]^+ Calculated value C20H19NO4Na 360.1206, measured value 360.1193.
References
[1] Journal of the American Chemical Society, 2016, vol. 138, # 5, p. 1698 - 1708
[2] Patent: WO2016/138288, 2016, A1. Location in patent: Page/Page column 124
