Sodium Hydroxide → Ethyl 4-bromo-3-methylthiophene-2-carboxylate

HRID 2269669ノート

反応式

HRID 2269669 の反応式
[CH3:1][C:2]1[CH:6]=[CH:5][S:4][C:3]=1[C:7]([O:9][CH2:10][CH3:11])=[O:8].[OH-].[Na+].[Br:14]Br>C(O)(=O)C.[Zn]>[Br:14][C:6]1[C:2]([CH3:1])=[C:3]([C:7]([O:9][CH2:10][CH3:11])=[O:8])[S:4][CH:5]=1

参加物

6

反応物 3

HCID 14798Sodium HydroxideHCID 24408BromineHCID 18347931Ethyl 3-methylthiophene-2-carboxylate

生成物 1

HCID 18347936Ethyl 4-bromo-3-methylthiophene-2-carboxylate収率 97%

試薬・触媒・溶媒 2

HCID 23994Zinc触媒HCID 176Acetic Acid溶媒

反応条件

温度
85 °C

実験手順

A solution of ethyl 3-methyl-2-thiophenecarboxylate (20.0 g, 0.118 mol) and sodium hydroxide (12.3 g, 0.307 mol) in acetic acid (75 mL) was heated to 60° C. Bromine (46.9 g, 0.294 mol) was added dropwise at such a rate so as to maintain the temperature of the reaction mixture at <85 ° C. When the addition was complete, the resulting solution was stirred at 85 ° C. for 6 hours, at which time analysis by gas chromatography/mass spectrometry showed complete conversion to ethyl 4,5-dibromo-3-methyl-2-thophenecarboxylate. The solution was allowed to cool to 50 ° C. and zinc dust (15.4 g, 0.236 mol) was added in 3 gram portions such that the exotherm was controlled to remain below 85 ° C. When the addition was completed, the resulting slurry was stirred at 85° C. for one hour. The solution was filtered hot through a small bed of celite. Water (300 mL) was added and the mixture was extracted with heptanes (300 mL). The organic phase was washed with water, then concetrated to dryness to give 26.9 g (89%) as an off white oil which slowly crystallized upon standing at ambient temperature. In a similar fashion, methyl 3-methyl-2-thiophenecarboxylate may be converted methyl-4bromo-3-methyl-2-thiophenecarboxyltate in 97% yield.

後処理

  1. temperatureto maintain the temperature of the reaction mixture at <85 ° C
  2. additionWhen the addition
  3. temperatureto cool to 50 ° C.
  4. customto remain below 85 ° C
  5. additionWhen the addition
  6. stirringthe resulting slurry was stirred at 85° C. for one hour
  7. filtrationThe solution was filtered hot through a small bed of celite
  8. additionWater (300 mL) was added
  9. extractionthe mixture was extracted with heptanes (300 mL)
  10. washThe organic phase was washed with water
  11. customto give 26.9 g (89%) as an off white oil which
  12. customslowly crystallized
  13. customupon standing at ambient temperature

出典と根拠

ORDレコード
ord-382de332d6b14f39a6b561ac2b326478
出典データセット
uspto-grants-2001_12
特許番号
US06329528B1

反応ノート

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