Reaction Steps
1-[4-[4-(1-Ethoxycarbonyl-1-methylethoxy)phenyl]butyryl]-2-(3,4-dimethylphenylmethyl)-4-methylsemicarbazide (1.20 g, 2.47 mmol) was dissolved in ethyl acetate (10 mL). Camphorsulfonic acid (0.64 g, 2.72 mmol) was added in one portion and the solution was heated to reflux for 1 h. The solution was cooled to rt and washed with sat'd aq. NaHCO3 (2×8 mL) followed by 1H HCl (2×8 mL ). The organic phase was dried (MgSO4) and concentrated to afford the title compound as a clear, colorless oil (1.08 g, 94%). 1H NMR (DMSO-d6) δ 7.04 (m, 3H), 7.03 (s, 1H), 6.93 (d, 1H, J=2 Hz), 6.68 (d, 2H, J=7 Hz), 4.72 (s, 2H), 4.13 (q, 2H, J=7 Hz), 3.08 (s, 3H), 2.53 (t, 2H, J=8 Hz), 2.47 (t, 2H, J=8 Hz), 1.80 (quint, 2H, J=7 Hz), 1.47 (s, 6H), 1.14 (t, 3H, J=7 Hz); 13C NMR (DMSO-d6) δ 174.0, 154.1, 147.1, 136.8, 135.9, 135.6, 135.3, 130.1, 129.8, 129.4, 125.7, 119.5, 79.2, 61.6, 48.4, 34.1, 27.7, 27.6, 25.7, 25.0, 20.0, 19.7, 14.6; IR (CHCl3) 2941, 1729, 1509, 1238, 1143 cm−1; Anal. Calcd. for C27H35N3O4: C, 69.65; H, 7.58; N, 9.03. Found: C, 69.25; H, 7.47; N, 8.88.
