Sodium bis(trimethylsilyl)amide → 2-(3,4-Dichloro-phenyl)-4-methyl-pent-2-enoic acid methyl ester

Temperature

0 °C

A suspension of isobutyl triphenylphosphonium bromide (2.02 g, 4.96 mmol) in dry tetrahydrofuran (5.4 mL) was cooled to 0° C. and then treated dropwise with a 1.0M solution of sodium bis(trimethylsilyl)amide (5 mL, 4.96 mmol). The bright orange reaction mixture was stirred at 0° C. for 1 h. The reaction mixture was then treated with a solution of (3,4-dichloro-phenyl)-oxo-acetic acid methyl ester (0.77 g, 3.30 mmol) in tetrahydrofuran (3 mL). The resulting reaction mixture was allowed to warm to 25° C. where it was stirred for 15 h. The reaction mixture was quenched with water (10 mL) and then concentrated in vacuo to remove tetrahydroftiran. The residue was further diluted with water (50 mL) and then extracted with ethyl acetate (2×75 mL). The combined organic layers were dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 97/3 hexanes/ethyl acetate) afforded the 2-(3,4-dichloro-phenyl)-4-methyl-pent-2-enoic acid methyl ester (749 mg, 83%) as a yellow viscous oil containing a 3.5:1 mixture of (E):(Z) isomers. The isomeric mixture was used without further separation and characterization.

1. customThe resulting reaction mixture
2. temperatureto warm to 25° C. where it
3. stirringwas stirred for 15 h
4. customThe reaction mixture was quenched with water (10 mL)
5. concentrationconcentrated in vacuo
6. customto remove tetrahydroftiran
7. additionThe residue was further diluted with water (50 mL)
8. extractionextracted with ethyl acetate (2×75 mL)
9. dry with materialThe combined organic layers were dried over sodium sulfate
10. filtrationfiltered
11. concentrationconcentrated in vacuo

ORD record

ord-7d1a06433d8a48c9ae257717464225c6

Source dataset

uspto-grants-2002_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06353111B1