反应详情

温度

-80 °C

In a four-necked flask cooled to −80° C. equipped with a mechanical stirrer, a thermometer, and a jacketed dropping funnel N-[2-(1,1-dimethylethoxy)-2-oxoethyl]-L-tryptophan 1,1-dimethylethyl ester (5 g; 13.35 mmol) was dissolved in CH3CN (25 mL). In the dropping funnel, cooled at −80° C., ethylene oxide (13 mL; 0.26 mol) was collected from the cylinder and then quickly dropped into the solution. Solid ytterbium triflate (0.83 g; 1.34 mmol) was added and after removal of the cooling bath the temperature was allowed to rise to r.t. The reaction was monitored by HPLC (Chromatographic method of Example 3, A)). After 15 h the solution was diluted with H2O (50 mL) and extracted with Et2O (150 mL). After evaporation of the solvent the crude was purified by flash chromatography (silica gel; n-hexane/ethyl acetate, 7:3 v/v) giving the desired product (4.32 g; 10.32 mmol).

1. customequipped with a mechanical stirrer
2. temperatureIn the dropping funnel, cooled at −80° C.
3. additionquickly dropped into the solution
4. customafter removal of the cooling bath the temperature
5. customto rise to r.t
6. additionAfter 15 h the solution was diluted with H2O (50 mL)
7. extractionextracted with Et2O (150 mL)
8. customAfter evaporation of the solvent the crude
9. customwas purified by flash chromatography (silica gel; n-hexane/ethyl acetate, 7:3 v/v)