Ethyl 4-bromocrotonate synthesis
- Product Name:Ethyl 4-bromocrotonate
- CAS Number:37746-78-4
- Molecular formula:C6H9BrO2
- Molecular Weight:193.04
623-70-1
37746-78-4
General procedure for the synthesis of ethyl (E)-4-bromobut-2-enoate from ethyl crotonate: To a round-bottomed flask containing ethyl (2E)-but-2-enoate (10.9 g, 87.6 mmol) and carbon tetrachloride (100 mL), N-bromosuccinimide (NBS, 17 g, 96 mmol) and azobisisobutyronitrile (AIBN, 4.3 g, 26 mmol). The reaction mixture was stirred at 80 °C for 12 hours. After completion of the reaction, the reaction mixture was diluted with dichloromethane (DCM) and washed sequentially with saturated sodium bicarbonate solution, water and brine. The organic layer was dried with anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent to give ethyl (E)-4-bromobut-2-enoate (7.5 g, 44% yield) as an oil.
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Yield:37746-78-4 81.2%
Reaction Conditions:
with bromine;triphenylphosphine in dichloromethane at 0; for 1.5 h;
Steps:
1.2
Step 2Triphenyl phosphine (295 g, 1.12 mol) and methylene chloride (665 mL) were introduced into a 3 L one-neck flask and were stirred for 10 minutes at 0° C. And then, bromine (179.3 g) dissolved in methylene chloride (665 mL) was slowly added as droplets therein for 1 hours. At this time, the temperature of the reactor was maintained to be 0° C. The reaction product was further stirred for 30 minutes after all of bromine was added. (E)-ethyl 4-hydroxybut-2-enoate (133 g, 1.02 mol) dissolved in methylene chloride (665 mL) was slowly added as droplets into the reaction mixture for 1 hours. At this time, the temperature of the reactor was also maintained to be 0° C. After all of (E)-ethyl 4-hydroxybut-2-enoate was added, the mixture was further stirred for 30 minutes at 0° C. (the reaction was confirmed with TLC, EtOAc:hexane=1:4). After washing the organic layer of the reaction product with water (900 mL×2), the organic layer was dried with anhydrous MgSO4, and then a large quantity of Ph3PO was extracted in company with the product by filtering and concentrating the same. The triphenyl phosphine oxide was eliminated by filtering the product, after adding n-hexane (1 L) therein and stirring the same for 30 minutes with a mechanical stirrer. (E)-ethyl 4-bromobut-2-enoate of 160 g was obtained with a yield of 81.2% by concentrating the filtered solution under a decompressed condition and distillating the concentrated solution under vacuum condition.1H-NMR (δ ppm, CDCl3, 400 Mz): 6.92 (m, 1H), 5.95 (m, 1H), 4.15 (q, 2H), 3.95 (m, 2H), 1.25 (t, 3H)
References:
KOLON LIFE SCIENCE, INC. US2012/46494, 2012, A1 Location in patent:Page/Page column 5
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