Methyl 2-bromo-4-methylbenzoate → Methyl 2-ethyl-4-methylbenzoate

To a stirred mixture of ZnBr2 (13 g, 57.72 mmol, 2.00 equiv) in THF (230 mL) under nitrogen at 0° C. was added dropwise EtMgBr (19.5 mL, 3 M in THF). After 30 minutes at 0° C., the temperature was lowered to −78° C. and Pd(dppf)Cl2 (2 g, 2.73 mmol, 0.09 equiv) was added followed by dropwise addition of a solution of methyl 2-bromo-4-methylbenzoate (6.6 g, 28.81 mmol, 1.00 equiv) in tetrahydrofuran (200 mL). The resulting mixture was allowed to slowly reach ambient temperature and stirred under nitrogen overnight. The reaction mixture was quenched by the careful addition of 20 mL NH4Cl (aq., sat.) and extracted with 3×100 mL of ethyl acetate. The combined organic layers were washed with 1×200 mL of brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified using silica gel column chromatography with ethyl acetate/petroleum ether (1:30) as eluent to yield 3.7 g (72%) of the title compound as a colorless oil.

1. customwas lowered to −78° C.
2. customwas allowed to slowly reach ambient temperature
3. customThe reaction mixture was quenched by the careful addition of 20 mL NH4Cl (aq., sat.)
4. extractionextracted with 3×100 mL of ethyl acetate
5. washThe combined organic layers were washed with 1×200 mL of brine
6. dry with materialdried over anhydrous sodium sulfate
7. concentrationconcentrated under reduced pressure
8. customThe residue was purified

ORD-Eintrag

ord-b72143ae51a84c86b3769a1f451c8840

Quelldatensatz

uspto-grants-2014_10

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08871790B2