3,5-bis(trimethylsilyl)-1-hydroxy-4-(methylthio)pyrazole

• 分子结构分类: 有机化合物 - 有机硫化合物 - 硫醚类
• 英文名称: 3,5-bis(trimethylsilyl)-1-hydroxy-4-(methylthio)pyrazole
• 英文别名: (1-Hydroxy-4-methylsulfanyl-5-trimethylsilylpyrazol-3-yl)-trimethylsilane
• 化学式: C₁₀H₂₂N₂OSSi₂
• 分子量: 274.534
• InChiKey: UYMRJRWGNWHNAE-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  1.93
• 重原子数：
  16
• 可旋转键数：
  3
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.7
• 拓扑面积：
  63.4
• 氢给体数：
  1
• 氢受体数：
  3

反应信息

• 作为产物：
  描述：

  二甲基二硫 、 3,5-bis(trimethylsilyl)-4-bromo-1-hydroxypyrazole 在 正丁基锂 作用下， 以 四氢呋喃 、 正己烷 为溶剂， 反应 4.62h， 以95%的产率得到3,5-bis(trimethylsilyl)-1-hydroxy-4-(methylthio)pyrazole
  参考文献：
  名称：

  Regioselective Introduction of Electrophiles in the 4-Position of 1-Hydroxypyrazole via Bromine−Lithium Exchange

  摘要：

  Two protocols for introduction of electrophiles at the 4-position of 1-hydroxypyrazoles have been developed. The first is deprotonation of 4-bromo-1-[(tert-butyldiphenylsilyl)oxy]pyrazole (6) with LDA to produce the 5-lithio derivative in which the silyl group migrates spontaneously from oxygen to C-5 affording 4-bromo-5-(tert-butyldiphenylsilyl)-1-lithoxypyrazole (8). Subsequent treatment with t-BuLi causes bromine-lithium exchange to give 5-tert-butyldiphenylsilyl-4-lithio-1-lithoxypyrazole which is trapped with electrophiles affording 4-substituted 5-(tert-butyldiphenylsilyl)-1-hydroxypyrazoles 9a-e in a one-pot sequence. The second is treatment of 4-bromo-1-hydroxypyrazole (5) with excess LDA and trimethylsilyl chloride to produce 3,5-bis(trimethylsilyl)-4-bromo-1-hydropyrazole (12), which upon sequential metalation with n-BuLi and reaction with electrophiles affords 4-substituted 3,5-bis(trimethylsilyl)-1-hydroxypyrazol 13a-e. The tert-butyldiphenylsilyl group of 9a and the trimethylsilyl groups of 12 can be removed selectively by treatment with tetrabutylammonium fluoride in THF in the presence of trifluoroacetic acid.

  DOI：

  10.1021/jo981970w

文献信息

• Regioselective Introduction of Electrophiles in the 4-Position of 1-Hydroxypyrazole via Bromine−Lithium Exchange
  作者：Thomas Balle、Per Vedsø、Mikael Begtrup

  DOI：10.1021/jo981970w

  日期：1999.7.1

  Two protocols for introduction of electrophiles at the 4-position of 1-hydroxypyrazoles have been developed. The first is deprotonation of 4-bromo-1-[(tert-butyldiphenylsilyl)oxy]pyrazole (6) with LDA to produce the 5-lithio derivative in which the silyl group migrates spontaneously from oxygen to C-5 affording 4-bromo-5-(tert-butyldiphenylsilyl)-1-lithoxypyrazole (8). Subsequent treatment with t-BuLi causes bromine-lithium exchange to give 5-tert-butyldiphenylsilyl-4-lithio-1-lithoxypyrazole which is trapped with electrophiles affording 4-substituted 5-(tert-butyldiphenylsilyl)-1-hydroxypyrazoles 9a-e in a one-pot sequence. The second is treatment of 4-bromo-1-hydroxypyrazole (5) with excess LDA and trimethylsilyl chloride to produce 3,5-bis(trimethylsilyl)-4-bromo-1-hydropyrazole (12), which upon sequential metalation with n-BuLi and reaction with electrophiles affords 4-substituted 3,5-bis(trimethylsilyl)-1-hydroxypyrazol 13a-e. The tert-butyldiphenylsilyl group of 9a and the trimethylsilyl groups of 12 can be removed selectively by treatment with tetrabutylammonium fluoride in THF in the presence of trifluoroacetic acid.