Triethylborane → 2-(R)-2-Pent-4enyloxy-but-3-en-1-ol

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Following the general procedure in Example 13A, 4-pentenol was added to butadiene monoepoxide, using the following quantities of reagents and solvents: Pd2dba3.CHCl3 (5.2 mg, 5.0 μmol), (S,S)-9 (11.8 mg, 15 μmol), DMAP (6.2 mg, 50 μmol), a 1.0 M solution of Et3B in THF (5.0 μL, 5.0 μmol), 4-pentenol (207 μL, 2.0 mmol), butadiene monoepoxide (81 μL, 1.0 mmol), CH2Cl2 (10 mL). The reaction time in this case was 4 h. Flash chromatography of the crude material (silica gel, 4:1 pentane-ether) afforded 131 mg (84%) of a colorless oil in 90% ee (separated by chiral GLC, Cyclosil B column, isothermal 120° C., (S)-(+)-isomerrt=9.33 min, (R)-(−)-isomerrt=9.68 min). [α]D=−33.2° (c 2.86, CHCl3); 1H NMR (300 MHz) δ 1.66 (quint 2H, J=7 Hz), 2.07-2.26 (m, 3H), 3.28-3.61 (m, 4H), 3.75-3.81 (m, 1H), 4.94 (d, 1H, J=11 Hz), 5.00 (d, 1H, J=17 Hz), 5.24 (d, 1H, J=9 Hz), 5.28 (d, 1H, J=17 Hz), 5.60-5.83 (m, 2H). 13C NMR (75.5 MHz) δ 28.9, 30.4, 65.2, 68.2, 81.6, 114.8, 118.7, 135.4, 138.2. Anal. Calc'd. for C9H16O2: C, 69.19; H, 10.32. Found: C, 69.23; H, 10.14.

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