Reaction Steps
Intermediate 56 was prepared as described above for the preparation of intermediate 52. From 534 mg of N-(Boc)-L-Tyrosine methyl ester and 500 mg of Intermediate 11B was prepared 900 mg of BOC-protected intermediate methyl ester (94% yield; 1H NMR (CDCl3, 300 MHz) δ7.9 (dd, 2H, 8.7, 5.2), 7.13 (t, 2H, J=8.6), 7.04 (d, 2H, J=8.5), 6.85 (d, 2H, J=8.6), 4.97 (d, 1H, J=7.9), 4.55 (m, 1H), 4.32 (t, 2H, J=6.8), 3.73 (s, 3H), 3.21 (t, 2H, J=6.7), 3.10-3.02 (m, 2H), 2.89 (q, 2H, J=7.5), 1.44 (s, 9H), 1.36 (t, 3H, J=7.5); From 850 mg of protected intermediate was prepared 900 mg of intermediate 56 as a solid. 1H NMR (DMSO-d6, 300 MHz) δ8.0 (br s, 2H), 7.91-7.87 (m, 2H), 7.30 (dt, 2H, J=8.8, 2.1), 7.14 (d, 2H, J=8.6), 6.90 (d, 2H, J=8.6), 4.27 (t, 2H, J=6.5), 4.12 (m, 1H), 3.11 (t, 2H, J=6.5), 3.0 (m, 2H), 2.86 (q, 2H, J=7.5), 1.26 (t, 3H, J=7.5); low resolution MS (ES+)m/e 414.85 (MH+).
