Allyl bromide → Methyl 3-bromo-2-but-3-en-1-ylbenzoate

Temperature

0 °C

To a flask charged with freshly prepared LDA (42 mmol) from n-BuLi and i-Pr2NH was dropped a solution of 3-bromo-2-methylbenzoic acid (3.0 g, 14 mmol) at −78° C. The reaction turned red right away. After stirring the mixture for 15 minutes, allyl bromide (8.4 g, 70 mmol) was dropped into the reaction. The reaction was allowed to warm up to 0° C. The reaction was quenched with 1N HCl, and extracted with EtOAc (100 mL×2). The extracts were combined, washed with brine, dried over sodium sulfate, and concentrated to give a light yellow oil. The oil was dissolved in toluene (30 mL) and methanol (10 mL) and treated with excess TMSdiazo methane (10 mL, 2.0 M in ether). Excess TMSdiazomethane was quenched with acetic acid when TLC indicated the reaction was done. The mixture was concentrated and crude product was purified by silica gel chromatography to afford methyl 3-bromo-2-but-3-en-1-ylbenzoate. 1H-NMR (500 MHz, CDCl3) δ ppm 7.78 (d, J=8.0 Hz, 1H), 7.76 (d, J=8.0 Hz, 1H), 7.15 (t, J=8.0 Hz, 1H), 5.98 (m, 1H), 5.12 (d, 17 Hz, 1H), 5.04 (d, J=10 Hz, 1H), 3.94 (s, 3H), 3.18 (m, 2H), 2.41 (m, 2H).

1. customThe reaction was quenched with 1N HCl
2. extractionextracted with EtOAc (100 mL×2)
3. washwashed with brine
4. dry with materialdried over sodium sulfate
5. concentrationconcentrated
6. customto give a light yellow oil
7. customExcess TMSdiazomethane was quenched with acetic acid when TLC
8. concentrationThe mixture was concentrated
9. customcrude product was purified by silica gel chromatography

ORD record

ord-79da9b7b137c455786228f20ccd6089b

Source dataset

uspto-grants-2014_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08673920B2