تفاعل #955923

معادلة التفاعل

ester

methyl 4-chloro-2-methylbenzoate

NMP

EtMgBr

→

methyl 4-ethyl-2-methylbenzoate

المردود 83.0%

المذيبات

THF

ether

ظروف التفاعل

المعالجة

1. 1
   أخرىwas used in the next step without further purification
2. 2
   أخرىgiving a red solution
3. 3
   أخرىquenched upon the addition of aq. HCl (1M, 10 ml)
4. 4
   استخلاصThe crude product was extracted with ether
5. 5
   غسيلThe combined organic layers were washed with water and brine
6. 6
   تجفيفdried over MgSO4
7. 7
   أخرىevaporated
8. 8
   أخرىThe residue was purified on silica gel (30% EtOAc/hexanes)

الإجراء التجريبي

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)).

المصدر