反应详情

A solution of pyridine sulfur trioxide (0.32 g) in DMSO (3.5 mL) was added dropwise to a stirred solution of compound [6a] (0.30 g) and triethylamine (0.40 g) in dichloromethane (4 mL) at −5-0° C. The mixture was stirred at the same temperature for 1 hour (TLC monitoring) and poured into cold water (15 mL). The mixture was stirred for 10 min at 0-5° C. The organic layer was separated, the water layer was extracted with dichloromethane (3×5 mL). The combined organic layers were washed with brine (3×10 mL), dried over sodium sulfate, filtered and evaporated under reduced pressure. A solution of the residue in methanol (1 mL) was cold to −10° C. and kept at the same temperature for 3 hours. The precipitated crystals were filtered, washed on filter with cold methanol (2×1 mL) and dried under reduced pressure to a constant weight to give 0.26 g (87% yield) of crystalline compound [4a] with 94% purity by HPLC.

1. stirringThe mixture was stirred for 10 min at 0-5° C
2. customThe organic layer was separated
3. extractionthe water layer was extracted with dichloromethane (3×5 mL)
4. washThe combined organic layers were washed with brine (3×10 mL)
5. dry with materialdried over sodium sulfate
6. filtrationfiltered
7. customevaporated under reduced pressure
8. customwas cold to −10° C.
9. waitkept at the same temperature for 3 hours
10. filtrationThe precipitated crystals were filtered
11. washwashed
12. filtrationon filter with cold methanol (2×1 mL)
13. customdried under reduced pressure to a constant weight