1-tert-butyl-3-methyl-1H-pyrazole-4,5-dicarboxylic acid dimethyl ester | 141981-55-7

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 唑类
• 英文名称: 1-tert-butyl-3-methyl-1H-pyrazole-4,5-dicarboxylic acid dimethyl ester
• 英文别名: Dimethyl 2-tert-butyl-5-methylpyrazole-3,4-dicarboxylate
• CAS: 141981-55-7
• 化学式: C₁₂H₁₈N₂O₄
• 分子量: 254.286
• InChiKey: GFEQWMYYBPVAMZ-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  1.6
• 重原子数：
  18
• 可旋转键数：
  5
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.58
• 拓扑面积：
  70.4
• 氢给体数：
  0
• 氢受体数：
  5

反应信息

• 作为产物：
  描述：

  2-methoxy-2,5-dimethyl-5-(2,2-dimethylethyl)-(Δ³)-1,3,4-oxadiazole 、 丁炔二酸二甲酯 以 氯仿 为溶剂， 反应 6.0h， 以20%的产率得到1-tert-butyl-5-methyl-1H-pyrazole-3,4-dicarboxylic acid dimethyl ester
  参考文献：
  名称：

  Studies of formal [1,5]-sigmatropic thermal rearrangements of dimethyl 3-alkyl-3-methyl-3H-pyrazole-4,5-dicarboxylates and dimethyl 4-alkyl-5-methyl-4H-pyrazole-3,4-dicarboxylates

  摘要：

  Studies of the thermal rearrangements of 3H-pyrazoles, 10a-e, in benzene/toluene, chloroform, and methanol solvents are described. The mechanism for rearrangement appears to be two-step, involving discrete ion-pair intermediates. Large rate enhancements for these rearrangements in methanol and cation trapping by methanol are consistent with the proposed mechanism. Observed rate constants for the rearrangements of 3H-pyrazoles 10c, 10d, and 10e in benzene-d6 were determined. Insight into the sense of rearrangement by an ion-pair mechanism is also provided by analysis of the H-1 NMR spectra of the product mixtures. 3H-Pyrazoles 10b and 10e rearrange to afford 4H-pyrazoles 13b and 13e, respectively, and the thermal rearrangements of these pyrazoles in benzene-d6 and methanol are described. Rate constants for the rearrangements of these more stable pyrazole isomers in benzene-d6 were also determined. Cation-trapping experiments with methanol suggest that the 4H-pyrazoles also rearrange by a two-step mechanism, involving discrete ion-pair intermediates. Furthermore, it appears that different ion-pair intermediates are formed from the 3H-pyrazoles 10b and 10e, compared to the 4H-pyrazoles 13b and 13e, on the basis of cation-trapping experiments.

  DOI：

  10.1021/ja00042a007