Reaktion #67393

Reaktionsgleichung

dichloromethane

bromoacetaldehyde diethylacetal

THF

Sodium hydride

→

Cyclopentadienyl Acetaldehyde Diethylacetal

Lösungsmittel

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeHexanes were decanted
2. 2
   workup.ADDITIONTHF (35 mL) was added to the sodium hydride
3. 3
   workup.ADDITIONA solution of 10 mL of freshly cracked cyclopentadiene in 10 mL of THF was slowly added dropwise
4. 4
   Temperaturreleasing heat
5. 5
   Sonstigeto give a brown solution and light precipitate
6. 6
   Filtrationthe mixture was filtered over Celite
7. 7
   Sonstigeto remove sodium bromide, and solvent
8. 8
   Sonstigewas removed from the filtrate in vacuo
9. 9
   Sonstigeto give to a brown oil
10. 10
    Filtrationthe mixture was again filtered through Celite
11. 11
    SonstigeSolvent was removed in vacuo
12. 12
    Sonstigeleaving a brown oil
13. 13
    workup.ADDITIONa 1:1 mixture of 1,2- and 1,3-isomers

Vorschrift

Sodium hydride (2.00 g, 60% wt. dispersion in mineral oil, 50.0 mmol) was washed with 40 mL hexanes. Hexanes were decanted and THF (35 mL) was added to the sodium hydride. A solution of 10 mL of freshly cracked cyclopentadiene in 10 mL of THF was slowly added dropwise, releasing heat and gas. This sodium cyclopentadienyl solution was added dropwise to a solution of bromoacetaldehyde diethylacetal (7.8 mL, 9.90 g, 50.0 mmol) in 45 mL THF to give a brown solution and light precipitate. After stirring overnight at 25° C., the mixture was filtered over Celite to remove sodium bromide, and solvent was removed from the filtrate in vacuo to give to a brown oil. To this was added 50 mL of dichloromethane and the mixture was again filtered through Celite. Solvent was removed in vacuo leaving a brown oil. 1H NMR data suggests a 1:1 mixture of 1,2- and 1,3-isomers. 1H NMR (CDCl3, 600 MHz): δ 6.50 (m, 1H), 6.43 (m, 1H), 6.40 (m, 1H), 6.29 (m, 1H), 6.27 (m, 1H), 6.14 (m, 1H), 4.66 (t, 1H), 4.61 (t, 1H), 3.67 (m, 4H), 3.51 (m, 4H), 2.96 (m, 2H), 2.75 (d, 1H), 2.72 (d, 1H) 1.21 (t, 12H). 13C{1H} NMR (CDCl3, 150.8 MHz): 144.16 (s), 142.05 (s), 135.01 (s), 133.47 (s), 132.30 (s), 131.54 (s), 128.68 (s), 128.51 (s), 102.72 (s), 102.52 (s), 61.26 (s), 61.08 (s), 44.07 (s), 41.33 (s), 35.24 (s), 34.62 (s), 15.30 (s).

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