反应详情

To a solution of L-serine (2.34 g, 12 mmol) in CHCl3 /DMF (60 mL, 5/1) was added chlorotrimethylsilane (1.52 mL, 12 mmol) and the mixture was vigorously stirred for 3 h at room temperature. Triethylamine (3.68 mL, 26.4 mmol) was then added slowly to maintain a gentle reflux, and the mixture was stirred for 15 min, after which Pb(NO3)2 (2.66 g, 8.0 mmol) was added, followed by the addition of 9-bromo-9-phenylfluorene (4.36 g, 14.4 mmol) in 30 mL of CHCl3. The mixture was vigorously stirred for 48 h at room temperature, methanol (1.2 mL, 30 mmol) was then added, and the mixture was stirred for an additional 30 min. The resulting mixture was filtered, the filter cake was washed with CHCl3 (2×50 mL), and the dark orange filtrate was evaporated to a residue which was partitioned between ether (200 mL) and aqueous 5% citric acid (60 mL). The aqueous layer was extracted with ether (2×50 mL), the combined organic solution was dried, filtered, and evaporated, and the residue was chromatographed (hexane/ethyl acetate, 8/2; hexane/THF, 6/4) to afford O-benzyl-N-(9-phenyl-9-fluorenyl)-L-serine (4.23 g, 81%) as a white solid.

1. temperatureto maintain a gentle reflux
2. stirringthe mixture was stirred for 15 min
3. stirringThe mixture was vigorously stirred for 48 h at room temperature
4. stirringthe mixture was stirred for an additional 30 min
5. filtrationThe resulting mixture was filtered
6. washthe filter cake was washed with CHCl3 (2×50 mL)
7. customthe dark orange filtrate was evaporated to a residue which
8. customwas partitioned between ether (200 mL) and aqueous 5% citric acid (60 mL)
9. extractionThe aqueous layer was extracted with ether (2×50 mL)
10. customthe combined organic solution was dried
11. filtrationfiltered
12. customevaporated
13. customthe residue was chromatographed (hexane/ethyl acetate, 8/2; hexane/THF, 6/4)