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0 °C

To a solution of 1,2,3,4-tetra-O-acetyl-α-L-fucopyranose (12 g, 36.1 mmol) and allyltrimethyl silane (11.48 mL, 72.2 mmol) in AcCN (60 mL) at 0° C. was added TMS-OTf (3.52 mL, 19.50 mmol). The reaction mixture was stirred at 0° C. for 18 hr and then at rt for 6 hr. The resulting red solution was diluted with CH2Cl2 (250 mL) and sat'd NaHCO3 (150 mL) was added carefully. The aqueous layer was separated and extracted with CH2Cl2 (2×50 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated. The residue was purified by flash chromatography on silica gel (220 g), eluting with 15% EtOAc in hexanes to give the title compound. 1H NMR (CDCl3, 400 MHz) δ 1.16 (d, J=6.4, 3H), 2.04 (s, 3H), 2.08 (s, 3H), 2.18 (s, 3H), 2.34 (m, 1H), 2.57 (m, 1H), 4.00 (m, 1H), 4.29 (dt, J=10.4, 7.3, 1H), 5.13 (m, 2H), 5.23 (dd, J=10.0, 3.4, 1H), 5.30 (dd, J=3.4, 1.9, 1H), 5.35 (dd, J=10.0, 5.6, 1H), 5.77 (m, 1H).

1. waitat rt for 6 hr
2. additionwas added carefully
3. customThe aqueous layer was separated
4. extractionextracted with CH2Cl2 (2×50 mL)
5. dry with materialThe combined organic layers were dried over Na2SO4
6. filtrationfiltered
7. concentrationconcentrated
8. customThe residue was purified by flash chromatography on silica gel (220 g)
9. washeluting with 15% EtOAc in hexanes