反応 #87479
ord-d6d5b1f3def849d68028b09b3407c755
反応方程式
反応物
反応条件
後処理
- 1温度the reaction mixture was heated
- 2温度at reflux under nitrogen
- 3その他The layers were separated
- 4抽出the aqueous layer was extracted two additional times with dichloromethane (25 mL)
- 5洗浄The combined organic layers were washed with brine (20 mL)
- 6乾燥dried over magnesium sulfate
- 7ろ過filtered through a pad of celite
- 8濃縮concentrated under reduced pressure
- 9その他The crude material was chromatographed with the Biotage SP4 automated chromatography unit (SNAP 25 g silica gel column)
- 10洗浄eluting with a gradient of 0-80% ethyl acetate in heptane
実験手順
To a solution of acetic acid (1R,2S,3S,4R,5S)-3,4-diacetoxy-1-acetoxymethyl-5-[4-chloro-3-(4-ethoxy-benzyl)-phenyl]-6,8-dioxa-bicyclo[3.2.1]oct-2-yl ester (Example 2; 344 mg, 0.569 mmol) in carbon tetrachloride (8 mL) was added N-bromosuccinimide (159 mg, 0.893 mmol) followed by the addition of 2,2′-azobisisobutyronitrile (AIBN, 8 mg, 0.05 mmol) and the reaction mixture was heated at reflux under nitrogen. After 16 hours, the reaction mixture was cooled to room temperature, water (50 mL) and dichloromethane (25 mL) were added and the resulting mixture was stirred for 24 hours at room temperature. The layers were separated and the aqueous layer was extracted two additional times with dichloromethane (25 mL). The combined organic layers were washed with brine (20 mL), dried over magnesium sulfate, filtered through a pad of celite, and concentrated under reduced pressure. The crude material was chromatographed with the Biotage SP4 automated chromatography unit (SNAP 25 g silica gel column) eluting with a gradient of 0-80% ethyl acetate in heptane to produce 316 mg (89% yield) of acetic acid (1R,2S,3S,4R,5S)-3,4-diacetoxy-1-acetoxymethyl-5-{4-chloro-3-[(4-ethoxy-phenyl)-hydroxy-methyl]-phenyl}6,8-dioxa-bicyclo[3.2.1]oct-2-yl ester as a mixture of diastereoisomers at the bis-benzylic position.