Reaktion #41147

Reaktionsgleichung

aluminum

1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylic acid methyl ester

N-bromosuccinimide

→

5-bromomethyl-1-tert-butyl-1H-pyrazole-4-carboxylic acid methyl ester

Ausbeute 95.2%

Lösungsmittel

carbon tetrachloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeThe reaction flask was fitted with a reflux condenser
2. 2
   Sonstigewas then illuminated with a 250 Watt sun lamp for 3 h
3. 3
   FiltrationAt this time, the reaction was filtered
4. 4
   Waschenwas rinsed with carbon tetrachloride
5. 5
   SonstigeThe filtrate was transferred to a separatory funnel
6. 6
   Waschenwas washed with water (1×50 mL)
7. 7
   TrocknenThe organics were dried over magnesium sulfate
8. 8
   Filtrationfiltered
9. 9
   Waschenrinsed with carbon tetrachloride
10. 10
    Einengenconcentrated in vacuo to a light yellow oil

Vorschrift

A solution of 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylic acid methyl ester (3.38 g, 17.22 mmol) (as described in Example 54, Step 2) in carbon tetrachloride (12.2 mL, 1.41M) at 25° C. was treated with N-bromosuccinimide (3.10 g, 17.41 mmol). The reaction flask was fitted with a reflux condenser. The set-up was wrapped with aluminum foil and was then illuminated with a 250 Watt sun lamp for 3 h. At this time, the reaction was filtered and was rinsed with carbon tetrachloride. The filtrate was transferred to a separatory funnel and was washed with water (1×50 mL) and a saturated aqueous sodium chloride solution (1×50 mL). The organics were dried over magnesium sulfate, filtered, rinsed with carbon tetrachloride and concentrated in vacuo to a light yellow oil. ISCO CombiFlash chromatography (120 g, 0-10% ethyl acetate/hexanes) afforded 5-bromomethyl-1-tert-butyl-1H-pyrazole-4-carboxylic acid methyl ester (4.51 g, 95%) as a clear oil. The material was used without further purification.

Quelle