反应详情

To a stirred mixture of 2-formyl-5-methylphenyl acetate (12.8 g, 71.8 mmol), carbon tetrabromide (47.6 g, 144 mmol), and 150 mL of DCM at 0° C. (translucent clear/yellow solution) under nitrogen was added a solution of triphenylphosphine (75 g, 287 mmol) in 140 mL of DCM dropwise over 15 min. A clear orange solution results initially. After 1 hr a purplish suspension results. The reaction was stirred for 2 hr at RT. After 2 hr 100 mL of heptane was added. The mixture was filtered to remove solids and the collected filtrate was concentrated under reduced pressure to give a dark brown gum. This was dissolved in minimal DCM and filtered through a silica gel plug which was flushed with 70% Heptane/30% EtOAc. The combined washes from the silica plug were concentrated under reduced pressure to give a yellow oil, 2-(2,2-dibromovinyl)-5-methylphenyl acetate (16.7 g). 1H NMR (400 MHz, DMSO-d6) δ 2.28 (s, 3H), 2.31 (s, 3H), 7.01 (s, 1H), 7.14 (d, J=8.0 Hz, 1H), 7.48 (s, 1H), 7.54 (d, J=8.0 Hz, 1H).

1. customA clear orange solution results initially
2. customAfter 1 hr a purplish suspension results
3. filtrationThe mixture was filtered
4. customto remove solids
5. concentrationthe collected filtrate was concentrated under reduced pressure
6. customto give a dark brown gum
7. filtrationfiltered through a silica gel plug which
8. customwas flushed with 70% Heptane/30% EtOAc
9. concentrationThe combined washes from the silica plug were concentrated under reduced pressure