2-Bromo-5-fluorobenzaldehyde → 1-Bromo-2-ethenyl-4-fluorobenzene

Participants

Reaction Conditions

Reaction Steps

21.12 g Methyltriphenylphosphonium bromide were suspended in 150 ml tetrahydrofuran and cooled in an ice bath. 21.68 ml n-butyl lithium (2.5 M in n-heptane) were added dropwise and the reaction mixture stirred at 0° C. for thirty minutes. Then 10.0 g commercially available 2-bromo-5-fluorobenzaldehyde were added slowly so that the reaction temperature did not exceed +5° C. After completion of the addition the cooling bath was removed and the reaction mixture stirred at room temperature for one hour. The reaction mixture was diluted by addition of 300 ml ethyl acetate and washed three times with portions of 120 ml brine. The organic phase was dried over MgSO4, the solvent removed in vacuo and the resulting residue purified on silica gel with the eluent heptane=>n-heptane:ethyl acetate=9:1 to obtain 7.9 g 1-Bromo-4-fluoro-2-vinyl-benzene as an oil.

Provenance & Evidence