反応 #89572

反応方程式

proton sponge

(S)-2-tert-butoxycarbonylamino-3-hydroxy-propionic acid benzyl ester

trimethyloxonium tetrafluoroborate

→

(S)-2-tert-butoxycarbonylamino-3-methoxy-propionic acid benzyl ester

収率 69.6%

溶媒

dichloromethane

反応条件

後処理

1. 1
   濃縮the solution was concentrated
2. 2
   workup.DISSOLUTIONthe residue was dissolved in ethyl acetate
3. 3
   ろ過the solution filtered through a pad of celite
4. 4
   洗浄The filtrate was washed with 1 M HCl and brine
5. 5
   乾燥The organic layers were dried over MgSO4
6. 6
   ろ過filtered
7. 7
   濃縮concentrated in vacuo

実験手順

To a solution of the compound of Formula XII(a), (S)-2-tert-butoxycarbonylamino-3-hydroxy-propionic acid benzyl ester (1.7 g, 5.76 mmol) in dichloromethane (50 mL) was added trimethyloxonium tetrafluoroborate (1.11 g, 7.50 mmol), followed by the portion-wise addition of proton sponge (1.61 g, 7.50 mmol). After stirring for 24 hrs at RT, the solution was concentrated, and the residue was dissolved in ethyl acetate, and the solution filtered through a pad of celite. The filtrate was washed with 1 M HCl and brine. The organic layers were dried over MgSO4, filtered, and concentrated in vacuo. Silica-gel flash chromatography with 5% to 15% ethyl acetate in hexanes afforded the compound of Formula XIII(b), (S)-2-tert-butoxycarbonylamino-3-methoxy-propionic acid benzyl ester (1.24 g, 69.6%) as a colorless oil. 1H NMR (300 MHz, CDCl3): δ (ppm) 7.35-7.29 (m, 5H), 4.90-4.87 (m, 1H), 4.51 (s, 2H), 3.92-3.87 (m, 1H), 3.80-3.78 (m, 1H), 3.56 (dd, 2H), 3.42 (dd, 1H), 3.33 (s, 3H), 1.42 (s, 9H).

出典