反応 #41999

反応方程式

n-butyl ketene

2a

(R, Z)-3-butyl-4-pentylideneoxetan-2-one

→

3-butyl-4-pentyl-oxetan-2-one

収率 90.0%

(3R, 4S)-3-butyl-4-pentyloxetan-2-one

収率 90.0%

溶媒

dichloromethane

dichloromethane

反応条件

後処理

1. 1
   洗浄as wash solvent
2. 2
   workup.ADDITIONPd/C (107 mg, 1 mol %, 5 wt %) was then added at one time under N.sub
3. 3
   ろ過filtered through a plug of Celite
4. 4
   濃縮concentrated
5. 5
   その他yielding a colorless oil
6. 6
   洗浄Flash chromatography with gradient elution (5→15% diethyl ether/hexanes; 2.5×35.0×5 cm pad)

実験手順

The purified n-butyl ketene dimer 2a, (5.1 mmol, 1.0 g) was dissolved in 40 mL dichloromethane (0.1 M) and transferred to a Parr bomb apparatus under a N.sub.2 atmosphere using an additional 10 mL dichloromethane as wash solvent. Pd/C (107 mg, 1 mol %, 5 wt %) was then added at one time under N.sub.2 atmosphere. The Parr bomb was then subjected to three consecutive evacuation-saturation cycles of hydrogen gas and then pressurized to 30 psi hydrogen gas pressure. Hydrogenation with shaking (Parr shaker) was continued for 30 min at this pressure and then the heterogeneous slurry was vacuum filtered through a plug of Celite, and concentrated yielding a colorless oil. Flash chromatography with gradient elution (5→15% diethyl ether/hexanes; 2.5×35.0×5 cm pad) gave 3-butyl-4-pentyl-oxetan-2-one (3a, 897 mg, 90%) as a colorless oil (>96% ee, chiral GC): Rf 0.47 (15% Et2O:hexanes ); IR (thin film) 1824 cm−1; 1H NMR (300 MHz, CDCl.sub.3) δ 4.54 (ddd, J=2.1, 3.6, 5.7 Hz, 1H), 3.59 (ddd, J=4.5, 5.4, 8.4 Hz, 1H), 1.46-1.84(m,6H), 1.31-1.44 (m, 8H), 0.88-0.94 (m, 6H); 13C NMR (500 MHz, CDCl3) δ 173.1, 76.5, 53.3, 32.2, 30.9, 30.5, 26.0, 24.4, 23.2, 23.2, 14.7, 14.5; ESI LRMS Calcd. for C12H22O2 [M+Li]: 205: Found:205.

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