反应详情

Analogously to Example 5, 8.45 g (50 mmol) of 2-(S)-bromo-3-hydroxypropionic acid in 200 ml of tetrahydrofuran is converted using 15.2 g (100 mmol) of 1,5-diazabicyclo[5.4.0]undec-5-ene into the DBU salt of (R)-glycidic acid. To the latter there are added in situ in methylene chloride at room temperature, 10.31 g (50 mmol) of dicyclohexyl carbodiimide and then, at 0°, 10.75 g (50 mmol) of N-allyl-N-phenylthiomethylammonium chloride. The resulting mixture is stirred for a further 3 hours at room temperature. The crystalline dicyclohexylurea is filtered off with suction, methylene chloride is added to the filtrate and the whole is washed with phosphate buffer having a pH of 8.0. The crude product obtained from the organic phase by drying over sodium sulphate and concentration by evaporation in vacuo is chromatographed over 500 g of silica gel using toluene/ethyl acetate (9:1) and the pure title compound is obtained in the form of a colourless oil.

1. customat 0°
2. filtrationThe crystalline dicyclohexylurea is filtered off with suction, methylene chloride
3. additionis added to the filtrate
4. washthe whole is washed with phosphate buffer
5. customThe crude product obtained from the organic phase
6. dry with materialby drying over sodium sulphate and concentration by evaporation in vacuo
7. customis chromatographed over 500 g of silica gel