Reaction Steps
The title compound is prepared according to the representative synthesis of aminophenol 2a except after the second step; H2N-Val-NHn-Bu is treated with salicylic acid under the standard amide formation conditions outlined in the first step. The resulting off-white solid is purified by silica gel chromatography (5:1 hexanes:ethyl acetate) to afford 2c as a white solid. M.p.=123-125° C. IR (neat): 3279 (w), 3090 (w, br), 2930 (m), 1620 (s), 1605 (s), 1547 (s), 1530 (s), 1454 (s), 1371 (m, br), 1229 (m), 756 (s), 643 (m) cm−1; 1H NMR (400 MHz, CDCl3): δ 12.07 (1H, s), 7.51 (1H, d, J=8.0 Hz), 7.40-7.36 (1H, m), 7.29 (1H, br s), 6.97 (1H, dd, J=8.4, 0.9 Hz), 6.85-6.81 (1H, m), 6.00 (1H, br s), 4.36 (1H, t, J=7.7 Hz), 3.39-3.30 (1H, m), 3.27-3.19 (1H, m), 2.25-2.17 (1H, m), 1.54-1.47 (2H, m), 1.39-1.30 (2H, m), 1.03 (3H, d, J=3.3 Hz), 1.01 (3H, d, J=3.2 Hz), 0.91 (3H, t, J=7.3 Hz); 13C NMR (100 MHz, CDCl3): δ 170.8, 169.8, 161.4, 134.5, 126.3, 119.0, 118.5, 114.4, 58.9, 39.6, 31.7, 31.6, 20.2, 19.3, 18.7, 13.8; HRMS Calcd for C16H25N2O3[M+H]+: 293.18652. Found: 293.18532. [α]20D=−34 (c=0.63, CHCl3).
