反应详情

A mixture of methyl 3-(4-chlorophenyl)-2-(ethoxycarbonylamino)propanoate (3.55 g, 12.4 mmol) in acetic acid (12 mL) and sulfuric acid (4 mL) was treated with paraformaldehyde (0.392 g, 13.0 mmol). After stirring at room temperature overnight, the mixture was added to ice (50-60 g), diluted with water (30 mL) and extracted with ethyl acetate (3ט50 mL). The combined organic phase was washed with saturated aqueous sodium chloride (25 mL), dried over MgSO4 and concentrated. Purification by silica gel chromatography (90 g column, 25-50% ethyl acetate in hexanes) gave 2-ethyl 3-methyl 7-chloro-3,4-dihydroisoquinoline-2,3(1 H)-dicarboxylate (2.19 g, 59%) as a clear, viscous oil. 1H NMR (CDCl3, 400 MHz) δ 7.12 (m, 3 H), 5.20 (m, ˜0.6 H), 4.98 (m, ˜0.4 H), 4.76 (m, 1 H), 4.53 (m, 1 H), 4.25 (m, 2 H), 3.65 (s, 3 H), 3.20 (m, 2 H), 1.35 (t, J=7 Hz, ˜1.8 H), 1.28 (t, J=7 Hz, ˜1.2 H) (mixture of rotamers). ESI+ MS found for C14H16ClNO4 m/z 298.0 (M+H, weak).

1. extractionextracted with ethyl acetate (3ט50 mL)
2. washThe combined organic phase was washed with saturated aqueous sodium chloride (25 mL)
3. dry with materialdried over MgSO4
4. concentrationconcentrated
5. customPurification by silica gel chromatography (90 g column, 25-50% ethyl acetate in hexanes)