Reaction Steps
Same procedure as above with N-Boc-Tyr(Bn)-Leu-OMe (1.034 g, 2.073 mmol), aqueous LiOH (1 M, 2.2 mL, 2.2 mmol) in THF (15 mL). A white solid was obtained (1.035 g, 100%) which was used in the next step without further purification. 1H NMR (300 MHz, CDCl3) δ 0.90 (d, J=5 Hz, 1H, Me2 Leu), 1.40 (s, 9H, (CH3)3), 1.60 (m, 3H, CH2—CH Leu), 3.00 (m, 2H, CH2), 4.29 (m, 1H, CHα), 4.44 (m, 1H, CHα), 4.88 (s, 2H, CH2 (Bn)), 5.29 (broad s, 1H, NHBoc), 6.70 (m, 1H, NH amide), 6.91 (d, J=5 Hz, 2 aromatic H), 7.12 (d, J=5 Hz, 2 aromatic H), 7.33-7.44 (m, 5 aromatic H). 3C NMR (75 MHz, CDCl3) δ 21.8, 22.9, 24.7 (CH-Me2 Leu), 28.2 ((CH3)3), 37.0 CH2 Leu), 41.1 (CH2 Tyr), 51.6 (CHα Leu), 55.7 (CHα Tyr), 70 (CH2 (Bn)), 80.4 (C(CH3)3), 114.9, 127.5, 127.9, 128.5, 128.9, 130.5, 137.0 (11 aromatic C), 155.8, 157.8 (Car-O, CO carbamate), 172.0, 176.8 (CO acid, CO amide).
