反应详情

To 2-mercaptoethanol (683.8 μl, 9.8 mmol) in buffer (100 ml, 150 mM NaCl, 100 mM sodium phosphate, pH 8.0, 5.0% DMF) was added di-bromomaleimide (1 g, 3.9 mmol) in DMF (2.5 ml, final concentration DMF 7.5%). The reaction was stirred for 30 min at RT and lithium chloride (20 g) was added. The aqueous reaction mixture was extracted with ethyl acetate (7×150 ml). The organic layers were combined, the solvent removed in vacuo and the residual material was purified by flash chromatography on silica gel (petroleum ether:ethyl acetate, gradient elution from 1:1 to 1:9). Fractions containing the product were collected and the solvent were removed in vacuo. The still impure product was purified by flash chromatography on silica gel (methanol:dichloromethane, gradient elution from 0.5-10.0% methanol) to afford the desired compound as a yellow solid (518 mg, 53%). λmax (50 mM sodium phosphate, pH 6.2, 40% MeCN, 2.5% DMF)/318 nm (ε/dm3 mol−1 cm−1 1855); 1H NMR (500 MHz, MeOD): δ=3.74 (t, 4H, J=6.4, 2×HO—CH2), 3.41 (t, 4H, J=6.3, 2×S—CH2) 13C NMR (125 MHz, MeOD): δ=168.5 (C), 137.2 (C), 62.3 (CH2), 34.4 (CH2); IR (solid, cm−1): 3344 (s), 2500 (m), 2078 (w); MS (EI) m/z, (%): 250 (M, 43), 232 (100), 161 (37); Mass calc. for C8H11O4NS2: 250.02077. Found: 250.02126; m.p. 46-50° C.

1. concentrationfinal concentration DMF 7.5%)
2. additionlithium chloride (20 g) was added
3. extractionThe aqueous reaction mixture was extracted with ethyl acetate (7×150 ml)
4. customthe solvent removed in vacuo
5. customthe residual material was purified by flash chromatography on silica gel (petroleum ether:ethyl acetate, gradient elution from 1:1 to 1:9)
6. additionFractions containing the product
7. customwere collected
8. customthe solvent were removed in vacuo
9. customThe still impure product was purified by flash chromatography on silica gel (methanol:dichloromethane, gradient elution from 0.5-10.0% methanol)