Reaction Steps
4-[4-(1-Ethoxycarbonyl-1-methyl-ethoxy)-phenyl] butyric acid (1.46 g, 4.96 mmol) was dissolved in ethyl acetate (10 mL). Oxalyl chloride (474 μL, 5.46 mmol) was added to this solution dropwise in the presence of a catalytic amount of N,N-dimethylformamide (30.6 μL, 0.39 mmol). Completion of acid chloride formation was verified by HPLC. This solution was then added dropwise to a suspension of N-Methyl-1-(3,4-dimethylphenylmethyl)hydrazine carboxamide methanesulfonate (1.50 g, 4.95 mmol) and pyridine (1.00 μL, 12.9 mmol) in ethyl acetate (15 mL) at 0° C. After stirring at 0° C. for 6 h, the solution was warmed to rt and washed with 1N HCl (2×20 mL), 5% aq. NaHCO3 (2×20 mL) and sat'd aq. NaCl. The organic layer was dried (MgSO4), filtered and concentrated to a yellow oil. The oil was purified by column chromatography (SiO2, 9:1 ethyl acetate:hexanes), to afford the title compound as a clear oil (1.48 g, 62%): 1H NMR (DMSO-d6, 60° C.) δ 9.42 (s, 1H), 6.97 (m, 5H), 6.71 (d, 2H, J=8 Hz), 6.23 (s, 1H), 4.46 (s, 2H), 4.15 (q, J=7 Hz), 2.59 (s, 3H), 2.43 (t, 2H, J=8 Hz ), 2.15 (s, 6H), 2.06 (t, 2H, J=8 Hz ), 1.70 (quint, 2H, J=7 Hz), 1.48 (s, 6H), 1.17 (t, 3H, J=7 Hz); 13C NMR (DMSO-d6) δ 174.0, 172.0, 158.7, 153.8, 136.4, 136.0, 135.9, 135.4, 130.2, 129.9, 129.7, 126.5, 119.5, 79.2, 61.6, 50.6, 34.4, 33.5, 27.6, 27.2, 25.7, 20.0, 19.7, 14.6; IR (CHCl3) 3009, 1669, 1509, 1142 cm−1; Exact Mass Calcd. for C27H38N3O5: 484.2811. Found: 484.2822.
