反应详情

(i) To a stirred solution of the ester 3 (90 mg, 0.21 mmol) in anhydrous THF (8 mL) lithium aluminum hydride (60 mg, 1.6 mmol) was added at 0° C. under argon. The cooling bath was removed after 1 h and the stirring was continued at 6° C. for 12 h and at room temperature for 6 h. The excess of the reagent was decomposed with saturated aq. Na2SO4, and the mixture was extracted with ethyl acetate and ether, dried (MgSO4) and evaporated. Flash chromatography of the residue with hexane/ethyl acetate (9:1) afforded unreacted substrate (12 mg) and a pure, crystalline diol 4 (35 mg, 48% based on recovered ester 3): 1H NMR (CDCl3+D2O) δ 0.079, 0.091, 0.100, and 0.121 (each 3H, each s, 4×SiCH3), 0.895 and 0.927 (9H and 9H, each s, 2×Si-t-Bu), 1.339 (1H, t, J˜12 Hz), 1.510 (1H, dd, J=14.3, 2.7 Hz), 2.10 (2H, m), 3.29 and 3.40 (1H and 1H, each d, J=11.0 Hz), 4.66 (1H, t, J˜2.8 Hz), 4.78 (1H, m), 4.92 (1H, t, J=1.7 Hz), 5.13 (1H, t, J=2.0 Hz), MS m/z (relative intensity) no M+, 345 (M+-t-Bu, 8), 327 (M+-t-Bu-H2O, 22), 213 (28), 195 (11), 73 (100).

1. customThe cooling bath was removed after 1 h
2. extractionthe mixture was extracted with ethyl acetate and ether
3. dry with materialdried (MgSO4)
4. customevaporated
5. customFlash chromatography of the residue with hexane/ethyl acetate (9:1) afforded unreacted substrate (12 mg)