反应详情

To a stirred solution of 2-tert-butoxycarbonylamino-3-methylpyridine (1.0 g, 4.8 mmol) in THF (10 mL) at −10° C. under Ar was added dropwise a solution of n-butyllithium (1.6 M, 6.0 mL, 9.6 mmol). The mixture was stirred for 30 min then added dropwise via cannula to a stirred solution of diethyl oxalate (2.1 g, 14.4 mmol) in THF (10 mL) at 0° C. under Ar. The mixture was stirred for 1 h and partitioned between water (50 mL) and ethyl acetate (30 mL). The aqueous layer was extracted with ethyl acetate (20 mL). The combined organic extracts were washed (water, brine), dried (sodium sulfate), concentrated in vacuo and purified by column chromatography [SiO2; ethyl acetate-heptane (1:1)] to give the product as a clear oil (0.61 g, 47%). IR νmax (film)/cm−1 3475, 2982, 2935, 2237, 1740, 1695, 1606, 1592, 1433, 1371, 1310, 1248, 1209, 1188, 1159, 1099, 1065, 1023, 912, 855, 785, 770, 732 and 645; NMR δH (400 MHz, CDCl3) 1.27 (3H, t, J 7Hz), 1.53 (9H, s), 3.18 (1H, d, J 17 Hz), 3.40 (1H, d, J 17 Hz), 4.27 (2H, q, J 7 Hz), 6.90 (1H, dd, J, 2.5,5 Hz), 7.43 (1H, d, J 7 Hz), 8.26 (1H, d, J 3.5 Hz).

1. stirringThe mixture was stirred for 1 h
2. custompartitioned between water (50 mL) and ethyl acetate (30 mL)
3. extractionThe aqueous layer was extracted with ethyl acetate (20 mL)
4. washThe combined organic extracts were washed (water, brine)
5. dry with materialdried (sodium sulfate)
6. concentrationconcentrated in vacuo
7. custompurified by column chromatography [SiO2; ethyl acetate-heptane (1:1)]