反应详情

A solution of 38.0 g of (3-bromo-benzyl)-triphenylphosphonium bromide, known from the literature, in 250 ml of tetrahydrofuran was treated at -10° C. with 8.75 g of potassium tert.-butylate and stirred for 3 minutes. A solution of 14.8 g of 4-bromobenzaldehyde was added dropwise to the yellow-orange suspension within 15 minutes. After stirring for 60 minutes the reaction mixture was concentrated. The residue was treated with ice-water and extracted with ethyl acetate/ether. The organic phases were washed with water and saturated aqueous sodium chloride solution, dried over magnesium sulfate and evaporated. The residue was chromatographed over silica gel with hexane and hexane/ether 99:1 and gave (E)-3,4'-dibromostilbene as colourless crystals, MS: m/z 338 (M+), as well as (Z)-3,4'-dibromostilbene as a colourless oil, MS: m/z 338 (M+).

1. stirringAfter stirring for 60 minutes the reaction mixture
2. concentrationwas concentrated
3. additionThe residue was treated with ice-water
4. extractionextracted with ethyl acetate/ether
5. washThe organic phases were washed with water and saturated aqueous sodium chloride solution
6. dry with materialdried over magnesium sulfate
7. customevaporated
8. customThe residue was chromatographed over silica gel with hexane and hexane/ether 99:1