反应详情

Compound 2 was prepared from 1 according to the literature procedure (J. Carbohydr. Chem. 8 (1989) 145) as follows Compound 1 of Example 1 (20.0 g) was refluxed in anhydrous benzene (500 mL) containing 3Å molecular sieves (20 g) for 1 h followed by the addition of di-n-butyltin oxide (24.0 g) and the refluxing was continued for 4 more h. To this tetraethylammonium bromide (7.0 g) and allyl bromide (80 mL) were added and refluxed for another 1 h followed by stirring at room temperature for 36 h. The reaction mixture was evaporated to dryness and the product was extracted with CH2Cl2, washed with 10% aqueous KF solution, ice cold 1M hydrochloric acid (HCl) and saturated sodium bicarbonate (NaHCO3) solution. Chromatography of the crude product on a column of Silica gel using ethyl acetate-hexane-ethanol =10:10:1 as eluant gave the titled compound 2 (16.2 g). [ α]D25 -3.5±2° (c 0.96, CHCl3). 1H n.m.r. (CDCl3 +D2O<5%) ∂: 5.97 (m, --CH=C), 5.35, 5.30, 5.24 and 5.20 (m, CH2 =C), 4.23 (m, O--CH2 --C=, H-1, J1,2 =7.5 Hz), 4.05 (d, J=3.5 Hz, H-4), 3.96-3.80 and 3.50-3.40 (m, O--CH2 --C, H-6a,b, H-5), 3.72 (dd, J=7.5, 9.5 Hz, H-2), 3.36 (dd, J=3.5, 9.5 Hz, H-3), 2.32 (t, J=7.0 Hz, CH2COO), 1.64 and 1.40 ((6 H, hydrogens of pentyl group). 13C n.m.r.(CD3OD) ∂: 176.0, 136.7, 117.3, 105.1 (C-1), 82.6 (C-3), 76.6 (C-5), 71.94, 71.89, 70.6, 67.6 (C-4 ), 62.7 (C-6), 52.0, 34.9, 30.5, 26.8, 25.9. Anal. Calcd for C16H28O8 ·H2O: C, 52.46; H, 8.20. Found: 52.84; H, 7.93.

1. customCompound 2 was prepared from 1 according to the literature procedure (J. Carbohydr. Chem. 8 (1989) 145)
2. additioncontaining 3Å molecular sieves (20 g) for 1 h
3. temperaturerefluxed for another 1 h
4. customThe reaction mixture was evaporated to dryness
5. extractionthe product was extracted with CH2Cl2
6. washwashed with 10% aqueous KF solution, ice cold 1M hydrochloric acid (HCl) and saturated sodium bicarbonate (NaHCO3) solution