反応 #567510

反応方程式

tert-butanol

H2SO4

MgSO4

5-bromo-thiophene-2-carboxylic acid

→

title compound

収率 94.4%

5-Bromo-thiophene-2-carboxylic acid tert-butyl ester

収率 94.4%

溶媒

CH2Cl2

反応条件

後処理

1. 1
   workup.STIRRINGAfter stirring for 1 minute
2. 2
   workup.STIRRINGthe reaction was stirred at room temperature for 18 h
3. 3
   その他The reaction was quenched with saturated NaHCO3
4. 4
   その他The layers were separated
5. 5
   抽出the aqueous layer was extracted with CH2Cl2
6. 6
   乾燥the combined organic layers were dried over MgSO4
7. 7
   濃縮The organic solution was concentrated
8. 8
   その他to give a clear oil which
9. 9
   その他was purified via medium pressure chromatography (3% EtOAc in hexanes)

実験手順

To a mixture of anhydrous MgSO4 (11.60 g, 96.4 mmol) in 100 mL CH2Cl2 was added concentrated H2SO4 (1.45 mL, 24.1 mmol) and the mixture was stirred for 15 minutes followed by addition of 5-bromo-thiophene-2-carboxylic acid (5.0 g, 24.1 mmol). After stirring for 1 minute, tert-butanol (11.6 g, 20 mmol) was added and the reaction was stirred at room temperature for 18 h. The reaction was quenched with saturated NaHCO3. The layers were separated, the aqueous layer was extracted with CH2Cl2, and the combined organic layers were dried over MgSO4. The organic solution was concentrated to give a clear oil which was purified via medium pressure chromatography (3% EtOAc in hexanes) to afford the title compound (4.97 g). 1H NMR (400 MHz, CDC13) δ 7.45 (d, 1H), 7.02 (d, 1H), 1.54 (s, 9H).

出典