反应步骤
To a solution of acid 134 (221 mg, 0.363 mmol) in DMF (3 mL) at 0° C. was added DIEA (127 μL, 0.726 mmol) and L-phenylalanine t-Butyl ester (94 mg, 0.36 mmol). After stirring for 15 min at 0° C., HBTU (138 mg, 0.363 mmol) was added and stirring was continued for 2 hr at 0° C. then 2 hr at room temperature. The reaction mixture was diluted with EtOAc and washed with cold aqueous NaHSO4 (10%), H2O and saturated aqueous NaCl then dried over Na2SO4. The crude product was purified by silica gel chromatography (0 to 20% gradient of MeOH in CH2Cl2, 10 CV) using a Biotage Horizons™ system. Compound 135 was obtained as a pale yellow coloured liquid (276 mg, 94%). 1H NMR (400 MHz, CDCl3) δ 1.24 (t, J=7.5, 3H), 1.34 (t, J=7.1, 12H), 1.40 (s, 9H), 1.76-1.79 (m, 4H), 1.93-2.06 (m, 2H), 2.19-2.30 (m, 2H), 2.21 (s, 3H), 2.22 (s, 3H), 2.31 (tt, J=5.9, 24.2, 1H), 2.57 (q, J=7.5, 2H), 2.76-2.82 (m, 2H), 3.06 (bd, J=6.3, 2H), 3.67 (bd, J=5.9, 2H), 4.13-4.22 (m, 8H), 4.74 (dt, J=5.9, 7.6, 1H), 5.86 (d, J=7.5, 1H), 6.68 (s, 1H), 7.06-7.08 (m, 2H), 7.21-7.25 (m, 3H): 31P (162 MHz, CDCl3) δ 24.93 (s, 2P).
