1-Bromo-2-methylpropane → 2-(3,4-Dichloro-phenyl)-4-methyl-pentanoic acid ethyl ester

온도

-78 °C

A solution of freshly prepared lithium diisopropylamide (4.88 mL of 0.29 M stock solution, 1.41 mmol) cooled to −78° C. was treated with (3,4-dichloro-phenyl)-acetic acid ethyl ester (300 mg, 1.28 mmol) in tetrahydrofuran/hexamethylphosphoramide (3.2 mL, 3:1). The resulting solution was stirred at −78° C. for 45 min. At this time, the reaction was treated with a solution of 1-bromo-2-methyl-propane (1.53 mL, 1.41 mmol) in hexamethylphosphoramide (1 mL). The reaction mixture was stirred at −78° C. for 6 h. The reaction was then warmed to 25° C. and stirred at 25° C. for 16 h. The reaction mixture was then quenched by the dropwise addition of saturated aqueous ammonium chloride solution (1 mL). This mixture was poured into water (50 mL) and extracted with ethyl acetate (3×50 mL). The organics were dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 50/50 hexanes/ethyl acetate) afforded 2-(3,4-dichloro-phenyl)-4-methyl-pentanoic acid ethyl ester (356.4 mg, 95.8%) as a clear oil: EI-HRMS m/e calcd for C14H18Cl2O2 (M+) 288.0683, found 288.0677.

1. stirringThe reaction mixture was stirred at −78° C. for 6 h
2. temperatureThe reaction was then warmed to 25° C.
3. stirringstirred at 25° C. for 16 h
4. customThe reaction mixture was then quenched by the dropwise addition of saturated aqueous ammonium chloride solution (1 mL)
5. additionThis mixture was poured into water (50 mL)
6. extractionextracted with ethyl acetate (3×50 mL)
7. dry with materialThe organics were dried over sodium sulfate
8. filtrationfiltered
9. concentrationconcentrated in vacuo

ORD 기록

ord-6a03c5747cf040ca8af957122ed8a08a

출처 데이터셋

uspto-grants-2003_03

DOI

10.6084/m9.figshare.5104873.v1

특허 번호

US06528543B1