反应详情

温度

0 °C

To a solution of N-phenylsulfonyl indole (5.14 g, 20 mmol) in dry THF (100 ml) under argon, and cooled to -65° C., was added t-butyl lithium (13 ml, 22 mmol, 1.7 M in pentane). The solution was allowed to warm to 0° C. and stirred for 1 hr. The above solution was added via canula to a stirred solution of dimethyloxalate (9.5 g, 80 mmol) in THF (250 ml) at 0° C. After 4 hrs at 0° C. the mixture was quenched with saturated aqueous NH4CI and extracted with ethyl acetate (3×100 ml). The dried (MgSO4) extract was evaporated in vacuo, and the residue purified by chromatography over silica gel eluting with hexane/ethyl acetate (b 10:1) to give the α-keto ester 12 (2.3 g, 34%). M.p. 111-112° C. (from ethyl acetate). IR (CHCl3) 3680, 3619, 3415, 3019, 1743, 1692, 1600, 1537 and 1372 cm-1. λmax (ε) (MeOH) 208 (23930), 265 (4460), 275 (4170), 312 (10040) nm. 1H NMR (CDCl3) δ8.06 (1H, d, J=8.5 Hz), 7.78 (2H, d, J=7.5 Hz), 7.58 (1H,d, J=8 Hz), 7.51-7.37 (5H, m), 7.29 (1H, t, J=7.6 Hz), 3.99 (3H, s). 13C NMR (CDCl3) δ177.2, 161.3, 138.5, 136.7, 135.8, 134.1, 129.0, 128.7, 128.5, 127.0, 124.8, 123.4, 122.2, 115.3, 53.3. Anal. calcd for C17H13NO5S C, 59.47; H, 3.82; N, 4.08. Found C, 59.42; H3.84; N, 3.99%.

1. customAfter 4 hrs at 0° C. the mixture was quenched with saturated aqueous NH4CI
2. extractionextracted with ethyl acetate (3×100 ml)
3. dry with materialThe dried (MgSO4)
4. extractionextract
5. customwas evaporated in vacuo
6. customthe residue purified by chromatography over silica gel eluting with hexane/ethyl acetate (b 10:1)