Reaction Steps
A mixture of 10 (440 mg, 1.4 mmol) and TBAF (1.0 M solution in THF, 4.7 mL, 4.7 mmol) in THF (3 mL) was stirred at 23° C. for 3 h, afterward a saturated solution of NaHCO3 was added, the solvent was removed and the aqueous phase was extracted with CHCl3. The organic extracts were dried (Na2SO4) and the solvent was removed. The residue was purified by flash-chromatography to afford 237 mg (87%) of (R)-2-[(2-methoxyethoxy)methoxy]pent-4-en-1-ol as a colourless oil: [c]D20=−55.0 (c 1.3, CHCl3); 1H NMR (CDCl3) δ 5.85-5.71 (m, 1H), 5.11-5.02 (m, 2H), 4.81 (d, J=7.5 Hz, 1H), 4.75 (d, J=7.5 Hz, 1H), 3.87-3.80 (m, 1H), 3.71-3.61 (m, 3H), 3.59-3.46 (m, 3H), 3.37 (s, 3H), 3.22 (bs, 1H), 2.36-2.19 (m, 2H); 13C NMR (CDCl3) δ 134.1, 117.3, 95.4, 81.0, 71.5, 67.3, 64.8, 58.9, 36.2. To a mixture of the above compound (240 mg, 1.25 mmol), allyl bromide (225 μL, 1.9 mmol) and a catalytic amount of TBAI in THF (12 mL), at 0° C., sodium hydride (60% dispersion in oil, 102 mg, 2.5 mmol) was added in small portions. After 30 min, the reaction mixture was allowed to warm to 23° C. and was stirred at the same temperature for 18 h. Subsequently, the reaction was quenched with a saturated solution of NH4Cl, the organic solvent was removed and the aqueous phase was extracted with CHCl3. The organic extracts were dried (Na2SO4) and the solvent was evaporated. The residue was purified by flash-chromatography (10:1 CHCl3/EtOAc) to afford 229 mg (80%) of 11 as a colourless oil. [α]D20, −5.2 (c 3.1, CHCl3); 1H NMR (CDCl3) δ 5.87-5.79 (m, 2H), 5.34 (dd, J=1.3, 19.1 Hz, 1H), 5.16-5.03 (m, 3H), 4.81 (d, J=7.0 Hz, 1H), 4.77 (d, J=7.0 Hz, 1H), 3.98-3.97 (m, 2H), 3.84-3.81 (m, 1H), 3.72 (t, J=5.0 Hz, 2H), 3.54 (t, J=5.0 Hz, 2H), 3.46-3.44 (m, 2H), 3.38 (s, 3H), 2.35-2.31 (m, 2H); 13C NMR (CDCl3) δ 134.6, 134.3, 117.3, 116.7, 94.6, 75.3, 72.1, 71.9, 71.6, 66.7, 58.9, 36.3.
