反应详情

Saccharine 5a (290 mg, 4.08 mmol) was dissolved in xylenes (10 mL) containing a small amount of activated charcoal (50 mg). DMF (2 drops) and freshly distilled SOCl2 (0.30 mL, 4.08 mmol) were added and the resulting mixture was heated to reflux for 15 hours. The solution was then cooled to room temperature and concentrated in vacuo to give a paste. The paste was dissolved in THF and the resulting solution was then added dropwise to a solution of MeMgCl (1.36 mL of a 3.0 M solution in THF, 4.08 mmol) in THF (7 mL). The resulting solution was stirred at 40° C. for 24 hours. After removal of solvent, the desired compound (124 mg, 40%) was obtained by flash chromatography (40 to 60% EtOAc in hexanes). To a solution of this material (100 mg, 0.44 mmol) in CH2Cl2 (50 mL) at −78° C. was added a 1.0 M solution of BBr3 (2.64 mL, 2.64 mmol) in CH2Cl2. The resulting mixture was stirred for 16 hours at ambient temperature. Careful quenching by the addition of H2O was followed by extraction with EtOAc. The combined organic extracts were washed with water and brine then dried over MgSO4. Compound 6a (54 mg, 58%) was delivered by flash chromatography (40 to 60% EtOAc in hexanes).

1. temperaturethe resulting mixture was heated
2. temperatureto reflux for 15 hours
3. concentrationconcentrated in vacuo
4. customto give a paste
5. customAfter removal of solvent