3,4-dibromo-5-formyl-1-vinylpyrazole | 923035-92-1

• 分子结构分类: 有机化合物 - 有机氧化合物
• 英文名称: 3,4-dibromo-5-formyl-1-vinylpyrazole
• 英文别名: 3,4-Dibromo-1-ethenyl-1H-pyrazole-5-carbaldehyde；4,5-dibromo-2-ethenylpyrazole-3-carbaldehyde
• CAS: 923035-92-1
• 化学式: C₆H₄Br₂N₂O
• 分子量: 279.919
• InChiKey: SADZSDOXYCZLON-UHFFFAOYSA-N

物化性质

• 沸点：
  208.3±40.0 °C(Predicted)
• 密度：
  2.03±0.1 g/cm3(Predicted)

计算性质

• 辛醇/水分配系数(LogP)：
  2.3
• 重原子数：
  11
• 可旋转键数：
  2
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.0
• 拓扑面积：
  34.9
• 氢给体数：
  0
• 氢受体数：
  2

反应信息

• 作为产物：
  描述：

  3,4,5-tribromo-1-vinylpyrazole 、 N,N-二甲基甲酰胺 在 正丁基锂 作用下， 以 四氢呋喃 、 正己烷 为溶剂， 反应 2.03h， 以66%的产率得到3,4-dibromo-5-formyl-1-vinylpyrazole
  参考文献：
  名称：

  The N-vinyl group as a protection group of the preparation of 3(5)-substituted pyrazoles via bromine–lithium exchange

  摘要：

  Treatment of 3,4,5-tribromopyrazole with 1,2-dibromoethane and triethylamine gave 3,4,5-tribromo-1-vinylpyrazole, which underwent regioselective bromine-lithium exchange at the 5-position. Subsequent addition of an electrophile gave 5-substituted 3,4-dibromo-1-vinylpyrazoles. These underwent bromine-lithium or bromine-magnesium exchange predominantly at the 4-position, with the regioselectivity between the 3- and 4-positions being influenced by the nature of the metal and the 5-substituent. The 5-substituted products were de-vinylated by mild treatment with KMnO4 affording 3-substituted pyrazoles. Alternatively, the 1-vinyl group could be used in ring-closing metathesis. Thus, 5-allylthio-1-vinylpyrazole produced 5H-pyrazolo[5,1-b] [1,3]thiazine upon treatment with Grubbs' second-generation catalyst. (c) 2006 Elsevier Ltd. All rights reserved.

  DOI：

  10.1016/j.tet.2006.10.009

文献信息

• The N-vinyl group as a protection group of the preparation of 3(5)-substituted pyrazoles via bromine–lithium exchange
  作者：Brian Iddon、Janne Ejrnæs Tønder、Masood Hosseini、Mikael Begtrup

  DOI：10.1016/j.tet.2006.10.009

  日期：2007.1

  Treatment of 3,4,5-tribromopyrazole with 1,2-dibromoethane and triethylamine gave 3,4,5-tribromo-1-vinylpyrazole, which underwent regioselective bromine-lithium exchange at the 5-position. Subsequent addition of an electrophile gave 5-substituted 3,4-dibromo-1-vinylpyrazoles. These underwent bromine-lithium or bromine-magnesium exchange predominantly at the 4-position, with the regioselectivity between the 3- and 4-positions being influenced by the nature of the metal and the 5-substituent. The 5-substituted products were de-vinylated by mild treatment with KMnO4 affording 3-substituted pyrazoles. Alternatively, the 1-vinyl group could be used in ring-closing metathesis. Thus, 5-allylthio-1-vinylpyrazole produced 5H-pyrazolo[5,1-b] [1,3]thiazine upon treatment with Grubbs' second-generation catalyst. (c) 2006 Elsevier Ltd. All rights reserved.