反应详情

The product from Step 5 (0.6 g, 2.9 mmol) was treated with 2 N KOH in ethanol under reflux for 4 h. Removal of ethanol and acidification of the residue with 2 N HCl gave the crude acid, which was dissolved in dichloromethane (mL) and treated with boron tribromide (1 M in hexane, mL, mmol) at 0 C for 1 h. The reaction was quenched with water and extracted with dichloromethane. The combined extracts were washed with brine and dried over MgSO4. Removal of solvents gave a residue which was taken up in 7:1 benzene/methanol and treated with excess trimethylsilyldiazo methane (1 m in hexane). Removal of solvents and purification of the residue by chromatography on silica gel afforded 0.48 (75% yield) of the title compound as an oil.

1. temperatureunder reflux for 4 h
2. customRemoval of ethanol and acidification of the residue with 2 N HCl
3. customgave the crude acid, which
4. customThe reaction was quenched with water
5. extractionextracted with dichloromethane
6. washThe combined extracts were washed with brine
7. dry with materialdried over MgSO4
8. customRemoval of solvents
9. customgave a residue which
10. customRemoval of solvents and purification of the residue by chromatography on silica gel