反应详情

To an oven dried test tube was added Pd2dba3.CHCl3 (5.2 mg, 5.0 μmol), chiral ligand (S,S)-9 (11.8 mg, 15 μmol), DMAP (6.2 mg, 50 μmol) and a stirbar. Several drops of CH2Cl2 were then added to wet the catalyst, and the test tube was immediately placed under reduced pressure (vacuum pump) for 10 sec and refilled with Ar. This purging procedure was repeated five times to ensure no oxygen remained in the reaction vessel. After being placed under an Ar atmosphere, freshly distilled and degassed methylene chloride was added (10 mL) and the resulting dark purple mixture was stirred at room temperature until it turned a deep orange color (roughly 15 min). During this time, the 3-butenol (172 μL, 2.0 μmol) and a 1.0 M solution of Et3B in THF was added (5.0 μL, 5.0 μmol). To the solution of catalyst and alcohol was added neat butadiene monoepoxide (81 μL, 1.0 μmol) and the solution immediately turned pale yellow. Stirring was continued for 4 h. The solvent was removed in vacuo. Flash chromatography of the crude material (silica gel, 4:1 pentane-ether) afforded 116 mg (82%) of 27 as a colorless oil in 90% ee (separated by chiral GLC, Cyclosil B column, isothermal 100° C., (S)-(+)-isomerrt=11.97 min, (R)-(−)-isomerrt=12.20 min). [α]D=−50.0° (c 2.20, CHCl3); 1H NMR (300 MHz): δ 2.09 (br s, 1H), 2.28-2.35 (m, 2H), 3.32-3.40 (m, 1H), 3.46-3.66 (m, 3H), 3.77-3.83 (m, 1H), 5.01 (d, IH, J=11 Hz), 5.10 (d, 1H, J=17 Hz), 5.23 (d, 1H, J=10 Hz), 5.28 (d, 1H, J=17 Hz), 5.60-5.84 (m, 2H); 13C NMR (75 MHz): δ 34.2, 65.3, 67.9, 81.7, 116.6, 118.7, 135.2, 135.2. Anal. Calcd. for C8H14O2: C, 67.57; H, 9.92; found C, 67.36; H, 9.80.

1. customTo an oven dried test tube
2. additionwas added Pd2dba3
3. additionrefilled with Ar
4. distillationfreshly distilled
5. customdegassed methylene chloride
6. additionwas added (10 mL)
7. customa deep orange color (roughly 15 min)
8. stirringStirring
9. waitwas continued for 4 h
10. customThe solvent was removed in vacuo