反应详情

A solution of the compound of step 1b above (27.1 g, 76.3 mmol) and THF (550 mL) was cooled to -75° C. Under a nitrogen atmosphere, a 2.5 M solution of n-butyllithium in hexane (62.6 mL, 156 mmol) was added dropwise over a 15 minute period. After stirring for 1 hour, saturated aqueous sodium bicarbonate was added dropwise to the reaction flask. The dry ice bath was removed and an additional portion of saturated aqueous sodium bicarbonate was added. The mixture was extracted with EtOAc (3×) and the combined organic phases dried over anhydrous sodium sulfate and concentrated in vacuo. The resulting residue was purified by flash chromatography on silica gel eluting with Et2O/hexane (1:6 to 1:5) to give 11.5 g (77% yield) of the title compound (1c) as an oil: [α]D≤ -92.1 (c 2.20, MeC)H); 1H NMR (CDCl3, 300 MHz) δ 4.45 (m, 1H), 3.53-3.24 (m, 2H), 2.25-1.85 (m, 5H), 1.48 (s, 9H); MS (CI) m/e 196 (M+H)+.

1. customThe dry ice bath was removed
2. additionan additional portion of saturated aqueous sodium bicarbonate was added
3. extractionThe mixture was extracted with EtOAc (3×)
4. dry with materialthe combined organic phases dried over anhydrous sodium sulfate
5. concentrationconcentrated in vacuo
6. customThe resulting residue was purified by flash chromatography on silica gel eluting with Et2O/hexane (1:6 to 1:5)