反应详情

The product from Example 11B (2.8 g, 6.1 mmol) in chloroform (50 mL) was treated with N-bromosuccinimide (1.2 g, 6.7 mmol), stirred at ambient temperature for 20 minutes, concentrated to dryness, heated at 130° C. under nitrogen for 15 minutes and allowed to cool to ambient temperature. The residue was purified on silica gel eluting with ethyl acetate:formic acid:water:hexane (38:1:1:40, then 38:1:1:20 then 38:1:1:10) to provide the title compound as the less polar diastereomer.

1. concentrationconcentrated to dryness
2. temperatureheated at 130° C. under nitrogen for 15 minutes
3. temperatureto cool to ambient temperature
4. customThe residue was purified on silica gel eluting with ethyl acetate:formic acid:water:hexane (38:1:1:40