反应详情

A solution of 201 (20 g, 0.090 mmol) in THF (200 mL) was cooled to −5° C. in an ice/methanol bath. NaOMe (19.45 g, 0.360 mol) was added and the mixture stirred for 30 minutes. After slow addition of a cooled solution of methyl formate (55.5 mL, 0.900 mol) in 60 mL THF, the mixture was stirred at room temperature for 24 hours. The mixture was poured into ice-water-HCl (˜50 mL conc. HCl in 500 mL H2O), stirred for 5 minutes and then transferred to a separatory funnel. The aqueous layer was extracted with ether (3×100 mL) and the pooled organic extracts were washed with brine, dried (MgSO4), and concentrated. The yellow residue was flash chromatographed (0-50% EtOAc-hexanes) to yield 203 (5.88 g, 26%) as a yellow oil. 1H NMR (CDCl3) δ 1.22 (s, 3H), 1.6-1.9 (m, 4H), 2.02 (d, J=14 Hz, 1H), 2.2-2.5 (2H), 2.91 (d, J=14 Hz, 1H), 3.9-4.1 (m, 4H), 5.86 (d, J=2.0 Hz, 1H), 7.37 (s, 1H); 13C NMR (CDCl3) 188.72, 166.86, 165.35, 165.12, 124.59, 124.25, 111.92, 106.39, 65.33, 65.17, 65.04, 64.89, 46.00, 29.87, 21.33, 20.74, 20.59.

1. stirringthe mixture was stirred at room temperature for 24 hours
2. stirringstirred for 5 minutes
3. customtransferred to a separatory funnel
4. extractionThe aqueous layer was extracted with ether (3×100 mL)
5. washthe pooled organic extracts were washed with brine
6. dry with materialdried (MgSO4)
7. concentrationconcentrated
8. customchromatographed (0-50% EtOAc-hexanes)