3,4-diethyl-1-(2-hydroxyethyl)-2,5-dimethylpyrrole | 137596-46-4

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 吡咯
• 英文名称: 3,4-diethyl-1-(2-hydroxyethyl)-2,5-dimethylpyrrole
• 英文别名: 2-(3,4-Diethyl-2,5-dimethylpyrrol-1-yl)ethanol
• CAS: 137596-46-4
• 化学式: C₁₂H₂₁NO
• 分子量: 195.305
• InChiKey: CAZBFLRHOSANCZ-UHFFFAOYSA-N

物化性质

• 沸点：
  312.9±30.0 °C(Predicted)
• 密度：
  0.96±0.1 g/cm3(Predicted)

计算性质

• 辛醇/水分配系数(LogP)：
  2.3
• 重原子数：
  14
• 可旋转键数：
  4
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.67
• 拓扑面积：
  25.2
• 氢给体数：
  1
• 氢受体数：
  1

反应信息

• 作为产物：
  描述：

  meso-3,4-diethyl-hexane-2,5-dione 、 C.I.酸性橙108 以 水 为溶剂， 生成 3,4-diethyl-1-(2-hydroxyethyl)-2,5-dimethylpyrrole
  参考文献：
  名称：

  Intermediates in the Paal-Knorr synthesis of pyrroles

  摘要：

  The mechanism of Paal-Knorr reaction between a 1,4-dicarbonyl compound and ammonia or a primary amine to form a pyrrole is explored. In aprotic solvents and in aqueous solutions near neutrality, d,l diastereomers of 3,4-dimethyl- and 3,4-diethyl-2,5-hexanediones (1r and 2r) formed pyrroles 1.3-57.0 times faster than the corresponding meso diastereomers (1m and 2m). This contradicts any intermediate, such as the enamine 15, which does not remain saturated at both the 3- and 4-positions through the rate-determining step. The demonstrated stereoisomeric difference in reactivity coupled with the following results support the hemiaminal (9) as the intermediate undergoing cyclization in the rate-limiting step of the Paal-Knorr reaction: (1) The reaction rate was adversely affected by increase in the size of the alkyl substituents on the dione. (2) Racemic 2,3-dimethyl-1,4-diphenyl-1,4-butanedione (3r) was more reactive toward ammonium acetate (2.2:1) and 2-aminoethanol (11.2:1) than the meso isomer (3m), ruling out the involvement of the less substituted enamine 14. (3) The relative rate of pyrrole formation of 1,4-diphenyl-1,4-butanedione (5) and its dimethoxy (6) and dinitro (7) derivatives (1:03:6) does not support cyclization of the imine (11) to the pyrrolinium ion (12). (4) The rates of reaction of 2,2,3,3-tetradeuterio-1,4-diphenyl-1,4-butanedione (5D) and perdeuterio-2,5-hexanedione (4D) were very close to those of unlabeled diketones, indicating the absence of a primary isotope effect in the reaction. (5) Neither the isomerization of the unreacted diastereomers of 1, 2, and 3 nor hydrogen exchange of 4D and 5D was detected during the reaction.

  DOI：

  10.1021/jo00024a040