Reaction Steps
A mixture of 3,4-dinitrophthalic acid (4.63 g, 18.1 mmol) and 2-(3-ethoxy-4-methoxyphenyl)-1-(methylsulfonyl)eth-2-ylamine (4.94 g, 18.1 g) in toluene (70 mL) was heated to reflux for 15 hours. The water was removed by a Dean-Stark trap. To the reaction mixture was added ethyl acetate (150 mL). The organic layer was extracted with water, sodium hydrogen carbonate (sat), brine (100 mL each), and dried over magnesium sulfate. The solvent was removed in vacuo to give a solid. The solid was recrystallized from ethanol (300 mL) to give 2-[1-(3-ethoxy-4-methoxyphenyl)-2-methylsulfonylethyl]-4,5-dinitroisoindoline-1,3-dione as an orange solid (4.35 g, 49% yield): mp, 122.0-124.0° C.; 1H NMR (CDCl3) δ1.47 (t, J=6.9 Hz, 3H, CH3), 2.93 (s, 3H, CH3), 3.65 (dd, J=3.9, 14.3 Hz, 1H, CHH), 3.86 (s, 3H, CH3), 4.10 (q, J=6.9 Hz, 2H, CH2), 4.56 (dd, J=11.4, 14.1 Hz, 1H, CHH), 5.90 (dd, J=3.9, 11.1 Hz, 1H, NCH), 6.84 (d, J=8.0 Hz, 1H, Ar), 7.07-7.11 (m, 2H, Ar), 8.16 (d, J=8.2 Hz, 1H, Ar), 8.60 (d, J=7.9 Hz, 1H, Ar); 13C NMR (CDCl3) δ14.66, 41.66, 49.57, 53.38, 55.98, 64.61, 111.61, 112.42, 120.64, 123.93, 126.18, 127.85, 131.93, 136.74, 138.10, 142.45, 148.77, 150.17, 161.57, 163.47; Anal Calcd for C20H19N3O10S+0.1 ethyl acetate: C, 48.78; H, 3.97; N, 8.37. Found: C, 48.50; H, 3.77; N, 8.07. (HNMR showed the sample contained ˜10% eq of ethyl acetate).
