反应详情

To a stirred suspension of methyl 4-nitroanthranilate (prepared from 4-nitroanthranilic acid, 14.2 g) in methanol (600 ml) was added propionaldehyde (5.04 g) followed by glacial acetic acid (7.2 ml). Sodium cyanoborohydride (4.56 g) was added and the reaction mixture stirred at room temperature for 16 hours. Further propionaldehyde (5.04 g) and sodium cyanoborohydride (4.56 g) were added and the mixture stirred for a further 24 hours. The solvent was evaporated and the residue partitioned between ethyl acetate and 10% potassium carbonate solution. The organic layer was separated and the aqueous re-extracted with ethyl acetate (2×100 ml). The combined organics were washed with saturated sodium chloride solution then dried (sodium sulphate) and evaporated to give the crude product, which was purified by column chromatography on silica using 10% diethyl ether/petroleum ether (60-80) to afford the required product (3.42 g, 20%). 1H NMR (250 MHz, DMSO-d6) δ0.98 (3H, t), 1.66 (2H, sextet), 3.26 (2H, dq), 3.86 (3H, s), 7.33 (1H, dd), 7.46 (1H, d), 7.88 (1H, t), 8.04 (1H, d).

1. stirringthe mixture stirred for a further 24 hours
2. customThe solvent was evaporated
3. customthe residue partitioned between ethyl acetate and 10% potassium carbonate solution
4. customThe organic layer was separated
5. extractionthe aqueous re-extracted with ethyl acetate (2×100 ml)
6. washThe combined organics were washed with saturated sodium chloride solution
7. dry with materialthen dried (sodium sulphate)
8. customevaporated
9. customto give the crude product, which
10. customwas purified by column chromatography on silica using 10% diethyl ether/petroleum ether (60-80)