反应详情

To a solution of ethyl 2-ethyl-4-hydroxycyclopentanecarboxylate (4.97 g, 26.7 mmol, prepared using II from Preparation #P.1, SS with NaOH)) in DMF (9 mL) was added TBDMS-Cl (4.83 g, 32.1 mmol) and imidazole (4.55 g, 66.8 mmol). The reaction mixture was stirred at ambient temperature for about 3 h. Heptane (30 mL) was added. The layers were separated and the bottom layer (DMF layer) was extracted with heptane (3×30 mL). The combined organic extracts were washed with water (2×30 mL), brine (30 mL), dried over anhydrous MgSO4, filtered and concd under reduced pressure. The material was purified by silica gel chromatography eluting with a gradient of 0-15% EtOAc in heptane to afford ethyl 4-(tert-butyldimethylsilyloxy)-2-ethylcyclopentanecarboxylate (5.16 g, 64%) as a colorless oil: 1H NMR (400 MHz, CDCl3) δ 4.45 (m, 1H), 4.11 (m, 2H), 3.08 (m, 1H), 2.34 (m, 1H), 2.18 (m, 1H), 1.75 (m, 2H), 1.57 (m, 1H), 1.41 (m, 1H), 1.25 (m, 3H), 1.10 (m, 1H), 0.90 (m, 3H), 0.87 (s, 9H), 0.03 (s, 6H).

1. customThe layers were separated
2. extractionthe bottom layer (DMF layer) was extracted with heptane (3×30 mL)
3. washThe combined organic extracts were washed with water (2×30 mL), brine (30 mL)
4. dry with materialdried over anhydrous MgSO4
5. filtrationfiltered
6. customThe material was purified by silica gel chromatography
7. washeluting with a gradient of 0-15% EtOAc in heptane