反应详情

To a room temperature suspension of diol 89 (352 mg, 1 mmol) and PPTS (12 mg, 0.05 mmol) in CH2Cl2 (10 mL) was added trimethyl orthoacetate (0.153 mL, 1.2 mmol). A clear solution resulted within 2 minutes. After stirring at RT for 3.5 h the reaction mixture was concentrated. The residue was dissolved in CH2Cl2 (10 mL) and acetyl bromide (0.089 mL, 1.2 mmol) added. After stirring at RT for 1.5 h the reaction mixture was concentrated. The residue was taken up in 2 mL MeOH (2 mL) to give an orange-brown suspension. K2CO3 (153 mg, 1.1 mol) was added and the resulting mixture stirred at room temperature for 2 h. It was then partitioned between sat NH4Cl and CH2Cl2. The aqueous phase was washed once more with CH2Cl2. The extracts were dried (MgSO4) and concentrated. The product 99 was purified by automated flash chromatography (40-80% EA/Hex).

1. customA clear solution resulted within 2 minutes
2. concentrationwas concentrated
3. dissolutionThe residue was dissolved in CH2Cl2 (10 mL)
4. stirringAfter stirring at RT for 1.5 h the reaction mixture
5. concentrationwas concentrated
6. customto give an orange-brown suspension
7. stirringthe resulting mixture stirred at room temperature for 2 h
8. customIt was then partitioned
9. washThe aqueous phase was washed once more with CH2Cl2
10. dry with materialThe extracts were dried (MgSO4)
11. concentrationconcentrated
12. customThe product 99 was purified by automated flash chromatography (40-80% EA/Hex)