반응 #41999

반응 방정식

n-butyl ketene

2a

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

→

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

수율 90.0%

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

수율 90.0%

용매

dichloromethane

dichloromethane

반응 조건

후처리

1. 1
   세척as wash solvent
2. 2
   workup.ADDITIONPd/C (107 mg, 1 mol %, 5 wt %) was then added at one time under N.sub
3. 3
   여과filtered through a plug of Celite
4. 4
   농축concentrated
5. 5
   기타yielding a colorless oil
6. 6
   세척Flash chromatography with gradient elution (5→15% diethyl ether/hexanes; 2.5×35.0×5 cm pad)

실험 절차

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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