反応 #955923

反応方程式

ester

methyl 4-chloro-2-methylbenzoate

NMP

EtMgBr

→

methyl 4-ethyl-2-methylbenzoate

収率 83.0%

溶媒

THF

ether

反応条件

後処理

1. 1
   その他was used in the next step without further purification
2. 2
   その他giving a red solution
3. 3
   その他quenched upon the addition of aq. HCl (1M, 10 ml)
4. 4
   抽出The crude product was extracted with ether
5. 5
   洗浄The combined organic layers were washed with water and brine
6. 6
   乾燥dried over MgSO4
7. 7
   その他evaporated
8. 8
   その他The residue was purified on silica gel (30% EtOAc/hexanes)

実験手順

4-Chloro-2-methylbenzoic acid (3 g, 17.6 mmol) was suspended in 12 ml of MeOH with 1 ml of concentrated H2SO4. The mixture was refluxed overnight, MeOH was evaporated and the residue was extracted with EtOAc, dried over MgSO4 filtered and evaporated to give methyl 4-chloro-2-methylbenzoate as a colorless viscous liquid (2.96 g, 92%) that was used in the next step without further purification. The ester (2.96 g, 16 mmol) was, under inert atmosphere, dissolved in THF (100 mL) and NMP (9 mL) and Iron (III) acetylacetonate (318 mg, 0.9 mmol) was added giving a red solution. Then EtMgBr (7 ml of 1M solution in ether) was added dropwise under vigorous stirring. The mixture turned dark brown and then violet and then was stirred for 15 more min. The reaction was diluted with ether and quenched upon the addition of aq. HCl (1M, 10 ml). The crude product was extracted with ether. The combined organic layers were washed with water and brine, dried over MgSO4 and evaporated. The residue was purified on silica gel (30% EtOAc/hexanes) to give methyl 4-ethyl-2-methylbenzoate as an oil (2.37 g, 83%). (1H NMR (500 MHz, CDCl3): δ 1.26 (t, 3H), 2.63 (dd, 2H), 3.9 (s, 3H), 7.1 (b, 2H), 7.85 (d, 1H)).

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