Phosphorus tribromide → 1-Bromo-2-(3-bromo-1-propen-1-yl)benzene

Participants

Reaction Steps

All of the o-bromocinnamylalcohol (159 mM) from Step A was dissolved in 300 ml of carbon tetrachloride under nitrogen and chilled to 0°. Then 100 ml of carbon tetrachloride containing phosphorous tribromide (5.62 ml; 59.8 mM) was added dropwise. After stirring at 0° for an additional hour the reaction was poured into ice water and partitioned. The aqueous layer was extracted once with methylene chloride and the combined organic layers were washed with cold 1.5 N aqueous sodium hydroxide. Drying over magnesium sulfate followed by solvent removal gave a pale yellow oil, which was purified by short path distillation at 0.2 ton. The o-bromocinnamyl bromide was distilled at 105° and 37.3 g (85% yield) was isolated. NMR (CDCl3): δ6.8-7.7 (m; 5H); 6.33 (AB:1H); 4.15 (d; 2H).

Provenance & Evidence