Reaction Steps
To a solution of (1R)-cyclopropanecarboxylic acid {2-[1-(3-ethoxy-4-methoxy-phenyl)-2-hydroxycarbamoyl-ethyl]-3-oxo-2,3-dihydro-1H-isoindol-4-yl}-amide (500 mg, 1.1 mmol) in acetonitrile (5 mL) was added isobutyryl chloride (0.15 mL, 1.4 mmol) at room temperature and kept for 24 hrs. The solution was extracted with ethyl acetate (50 mL) and sodium hydrogen carbonate (50 mL, sat). The organic layer was dried over MgSO4. Filtration and removal of solvent gave (1R)-cyclopropanecarboxylic acid {2-[1-(3-ethoxy-4-methoxy-phenyl)-2-isobutyryloxycarbamoyl-ethyl]-3-oxo-2,3-dihydro-1H-isoindol-4-yl}-amide (380 mg, 66% yield): mp, 107–109° C.; 1H NMR (DMSO-d6) δ 0.86–0.89 (m, 4H, 2CH2), 1.10 (d, J=7 Hz, 6H, 2CH3), 1.31 (t, J=7 Hz, 3H, CH3), 1.73–1.81 (m, 1H, CH), 2.62–2.73 (m, 1H, CH), 3.02–3.05 (m, 2H, CH2), 3.73 (s, 3H, CH3), 3.96–4.05 (m, 2H, CH2), 4.19 (d, J=18 Hz, 1H, NCHH), 4.59 (d, J=18 Hz, 1H, NCHH), 5.67 (t, J=8 Hz, 1H, NCH), 6.86–6.94 (m, 3H, Ar), 7.19 (d, J=8 Hz, 1H, Ar), 7.50 (d, J=8 Hz, 1H, Ar), 8.23 (d, J=8 Hz, 1H, Ar), 10.54 (s, 1H, NH), 11.86 (s, 1H, NH); 13C NMR (DMSO-d6) δ 7.76, 14.69, 15.46, 18.65, 31.27, 34.64, 46.59, 51.07, 55.47, 63.80, 111.93, 112.09, 116.82, 117.32, 117.50, 119.27, 131.23, 132.77, 136.98, 142.25, 147.95, 148.58, 166.61, 168.04, 171.72, 174.29; Anal Calcd for C28H33N3O7+0.11 H2O: C, 63.99; H, 6.37; N, 8.00; H2O, 0.38. Found: C, 63.64; H, 6.37; N, 7.70; H2O, 0.39.
