反应详情

A 2 M solution of lithium diisopropylamide (LDA) was prepared by the addition of N-butyllithium (8.0 mL, 2.5 M, 20 mmol) to diisopropylamine (2.4 g, 24 mmol) in THF (2 mL) at 0° C. After stirring for 1 h, the LDA solution (6.6 mL, 13.2 mmol) was added to a flask containing 1-4 (1.0 g, 3.3 mmol) and chloroiodomethane (2.9 g, 17 mmol) in THF (33 mL) at −78° C. The mixture was stirred at −78° C. for 2 h then warmed to room temperature and diluted with EtOAc (30 mL). The solution was washed with saturated aqueous sodium bicarbonate (2×20 mL) and brine (1×20 mL) and the organic layer was dried over sodium sulfate, filtered and concentrated in vacuo. The crude material was purified by silica gel chromatography (20-40% EtOAc/hexanes) to afford 1-5 as a white solid.

1. stirringThe mixture was stirred at −78° C. for 2 h
2. washThe solution was washed with saturated aqueous sodium bicarbonate (2×20 mL) and brine (1×20 mL)
3. dry with materialthe organic layer was dried over sodium sulfate
4. filtrationfiltered
5. concentrationconcentrated in vacuo
6. customThe crude material was purified by silica gel chromatography (20-40% EtOAc/hexanes)