Reacción #955923

Ecuación de reacción

ester

methyl 4-chloro-2-methylbenzoate

NMP

EtMgBr

→

methyl 4-ethyl-2-methylbenzoate

Rendimiento 83.0%

Disolventes

THF

ether

Condiciones de reacción

Tratamiento posterior

1. 1
   Otrowas used in the next step without further purification
2. 2
   Otrogiving a red solution
3. 3
   Otroquenched upon the addition of aq. HCl (1M, 10 ml)
4. 4
   ExtracciónThe crude product was extracted with ether
5. 5
   LavadoThe combined organic layers were washed with water and brine
6. 6
   Secadodried over MgSO4
7. 7
   Otroevaporated
8. 8
   OtroThe residue was purified on silica gel (30% EtOAc/hexanes)

Procedimiento

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)).

Fuente