Reaktion #89688

Reaktionsgleichung

phenylselenyl chloride

2-allylcyclopentanone

lithium bis(tri-methylsilyl)amide tetrahydrofuran

→

2-allyl-5-(phenylselanyl)cyclopentanone

Ausbeute 71.0%

Lösungsmittel

tetrahydrofuran

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigetemperature below −55° C
2. 2
   workup.ADDITIONOnce the addition
3. 3
   workup.STIRRINGthe mixture stirred at −60 to −70° C. for 30 min
4. 4
   Temperaturto warm to 0° C
5. 5
   SonstigeThe reaction was quenched by addition of the solution to a rapidly stirred mixture of ethyl acetate (500 mL) and 5% aqueous citric acid (200 mL)
6. 6
   Sonstigethe organic layer was separated
7. 7
   ExtraktionThe aqueous solution was extracted with ethyl acetate (2×100 mL)
8. 8
   Waschenthe combined organic solution was washed with saturated aqueous sodium chloride (200 mL)
9. 9
   Trocknendried (MgSO4)
10. 10
    Einengenconcentrated in vacuo
11. 11
    workup.DISSOLUTIONThe residue was dissolved in heptane
12. 12
    Wascheneluted with 2:1 heptane/dichloromethane

Vorschrift

While under a nitrogen, a solution of 2-allylcyclopentanone (12.4 g, 100 mmol) in anhydrous tetrahydrofuran (100 mL) was cooled to −70° C. and treated with 1 N lithium bis(tri-methylsilyl)amide/tetrahydrofuran (200 mL, 200 mmol) at a rate to keep pot temperature below −55° C. Once the addition was complete, the mixture was stirred at −60 to −70° C. for one additional hour. A second solution of phenylselenyl chloride (19.5 g, 102 mmol) in anhydrous tetrahydrofuran (50 mL) was added dropwise and the mixture stirred at −60 to −70° C. for 30 min, then allowed to warm to 0° C. The reaction was quenched by addition of the solution to a rapidly stirred mixture of ethyl acetate (500 mL) and 5% aqueous citric acid (200 mL), and the organic layer was separated. The aqueous solution was extracted with ethyl acetate (2×100 mL) and the combined organic solution was washed with saturated aqueous sodium chloride (200 mL), dried (MgSO4), and concentrated in vacuo. The residue was dissolved in heptane and loaded onto a silica gel column (˜600 cc) and eluted with 2:1 heptane/dichloromethane, then with 1:1 heptane/dichloromethane to afford 2-allyl-5-(phenylselanyl)cyclopentanone (19.7 g, 71%) as a pale yellow oil. NMR (CDCl3): δ 7.40-7.50 (m, 2 H), 7.05-7.25 (m, 3 H), 5.50-5.70 (m, 1 H), 4.80-4.95 (m, 2 H), 3.45-3.75 (m, 1 H), 2.30-2.50 (m, 1 H), 1.80-2.25 (m, 5 H), 1.50-1.75 (m, 1 H). MS (M+1): 279.1/280.9 (for 2 major isotopes of Se).

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