Reaktion #939950

Reaktionsgleichung

phosphorus-trichloride

Tygon

sodium sulfite

(1S,4R)-bicyclo[2.2.1]heptane-2-carboxylic acid

bromine

→

(4S)-2-bromobicyclo[2.2.1]heptane-1-carboxylic acid

Lösungsmittel

ether

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONAfter the addition
2. 2
   Temperaturthe reaction mixture was heated in a silicone oil bath at 80° C. for 4 h
3. 3
   TemperaturAfter this time, the reaction was cooled to 10° C.
4. 4
   TemperaturThe reaction was then heated to 80° C
5. 5
   TemperaturThe reaction was then cooled to room temperature
6. 6
   SonstigeThe ethereal solution was transferred to a separation funnel
7. 7
   Waschenwashed with 1M sodium sulfite (2×500 mL), water (1×500 mL), and brine (1×500 mL)
8. 8
   TrocknenThe organic layer was dried over MgSO4
9. 9
   Filtrationfiltered
10. 10
    Einengenconcentrated in vacuo
11. 11
    Sonstigeto afford an oil
12. 12
    workup.STIRRINGthe mixture was stirred vigorously
13. 13
    workup.WAITAfter 20 min
14. 14
    Sonstigea fine white precipitate formed
15. 15
    Filtrationwhich was filtered
16. 16
    Waschenwashed with pentane (20 mL)
17. 17
    Sonstigeair dried under a gentle vacuum

Vorschrift

To a 50 mL round-bottomed flask was added (1S,4R)-bicyclo[2.2.1]heptane-2-carboxylic acid (9.84 g, 70 mmol) and bromine (4.10 ml, 80 mmol). The suspension was stirred at room temperature until dissolution. Trichlorophosphine (0.30 ml, 3.4 mmol) was then added slowly and drop wise (significant exotherm observed). A reflux condenser was fitted to the flask with a nitrogen gas inlet and gas outlet (Tygon tubing) running into a scrubber solution of sodium sulfite (1 M, 200 mL). After the addition was complete, the reaction mixture was heated in a silicone oil bath at 80° C. for 4 h. After this time, the reaction was cooled to 10° C. and phosphorus-trichloride (4.23 ml, 48.3 mmol) was added drop-wise. The reaction was then heated to 80° C. During this time the color intensity of the reaction decreased, and after 8 h, the reaction mixture appeared dark orange. The reaction was then cooled to room temperature and diluted with ether (1 L). The ethereal solution was transferred to a separation funnel and washed with 1M sodium sulfite (2×500 mL), water (1×500 mL), and brine (1×500 mL). The organic layer was dried over MgSO4, filtered, and concentrated in vacuo to afford an oil. Ice cold pentane (50 mL) was then added to the crude product, and the mixture was stirred vigorously. After 20 min, a fine white precipitate formed, which was filtered and washed with pentane (20 mL) and then air dried under a gentle vacuum to afford (4S)-2-bromobicyclo[2.2.1]heptane-1-carboxylic acid (100.2 g, 457 mmol) as a white solid material.

Quelle