反应详情

温度

-30 °C

Lithium diethylamide was prepared by adding (5 min) nBuLi in hexanes (94 mL, 150 mmol) to a solution of diisopropylamine (22.80 mL, 160 mmol) in THF (50 mL) at −30° C. (dry ice/acetone) under N2. After 20 min, ethyl 1,4-dioxaspiro[4.5]decane-8-carboxylate (21.43 g, 100 mmol) in THF (25 mL) was added over 5 min. After 20 min, iodomethane (28.4 g, 200 mmol) in THF (25 mL) was added over 5 min. The resulting solution was stirred at −30° C. for 20 min and then allowed to slowly warm to room temperature overnight under N2. The reaction was quenched with water (200 mL). The solution was concentrated to remove THF. The aqueous solution was extracted with CH2Cl2 (3×100 mL) and the organic layer dried (MgSO4), filtered, and concentrated to yield ethyl 8-methyl-1,4-dioxaspiro[4.5]decane-8-carboxylate (22 g, 96 mmol, 96% yield) as a yellow oil. LCMS: m/z 229 (M+H). 1H NMR (500 MHz, CHLOROFORM-d) δ ppm 4.13 (2 H, q, J=7.22 Hz), 3.92 (4 H, s), 2.06-2.16 (2 H, m), 1.57-1.66 (4 H, m), 1.51 (2 H, dd, J=12.97, 4.12 Hz), 1.24 (3 H, t, J=7.17 Hz), 1.17 (3 H, s).

1. waitAfter 20 min
2. temperatureto slowly warm to room temperature overnight under N2
3. customThe reaction was quenched with water (200 mL)
4. concentrationThe solution was concentrated
5. customto remove THF
6. extractionThe aqueous solution was extracted with CH2Cl2 (3×100 mL)
7. dry with materialthe organic layer dried (MgSO4)
8. filtrationfiltered
9. concentrationconcentrated