4,4-dimethyl-6(Z)-(bromomethylidene)tetrahydro-2-pyranone | 136358-15-1

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 内酯类
• 英文名称: 4,4-dimethyl-6(Z)-(bromomethylidene)tetrahydro-2-pyranone
• 英文别名: (6Z)-6-(bromomethylidene)-4,4-dimethyloxan-2-one
• CAS: 136358-15-1
• 化学式: C₈H₁₁BrO₂
• 分子量: 219.078
• InChiKey: JFSMJDXEJHZQBD-WAYWQWQTSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  2.1
• 重原子数：
  11
• 可旋转键数：
  0
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.62
• 拓扑面积：
  26.3
• 氢给体数：
  0
• 氢受体数：
  2

反应信息

• 作为产物：
  描述：

  3,3-Dimethyl-5-hexynoic acid 在 sodium hydroxide 、 溴 、 silver nitrate 作用下， 生成 4,4-dimethyl-6(Z)-(bromomethylidene)tetrahydro-2-pyranone
  参考文献：
  名称：

  Stereoselective Z- and E-bromoenol lactonization of alkynoic acids

  摘要：

  We have found that treatment of the silver salt of a 4- or 5-terminal alkynoic acid with bromine results in clean formation of the corresponding Z-bromo enol lactone, the result of a formal cis addition of carboxylate and bromine across the triple bond. This Z-bromo enol lactonization is highly stereoselective and gives good yields in systems that bear substituents on the internal methylene groups; yields with unsubstituted or terminally substituted alkynoic acids are modest. The E-bromo enol lactonization reaction, reported by us previously (Krafft, G. A.; Katzenellenbogen, J. A. J. Am. Chem. Soc. 1981, 103, 5459), has a broader scope and, with modifications, can be performed with high reliability. Mercury(II) salts equilibrate the Z- and E-bromo enol lactones, presumedly by a mercuric ion addition-elimination mechanism. These three reactions provide access to an array of stereoisomeric bromo enol lactone systems.

  DOI：

  10.1021/jo00024a035

文献信息

• Stereoselective Z- and E-bromoenol lactonization of alkynoic acids
  作者：Wei Dai、John A. Katzenellenbogen

  DOI：10.1021/jo00024a035

  日期：1991.11

  We have found that treatment of the silver salt of a 4- or 5-terminal alkynoic acid with bromine results in clean formation of the corresponding Z-bromo enol lactone, the result of a formal cis addition of carboxylate and bromine across the triple bond. This Z-bromo enol lactonization is highly stereoselective and gives good yields in systems that bear substituents on the internal methylene groups; yields with unsubstituted or terminally substituted alkynoic acids are modest. The E-bromo enol lactonization reaction, reported by us previously (Krafft, G. A.; Katzenellenbogen, J. A. J. Am. Chem. Soc. 1981, 103, 5459), has a broader scope and, with modifications, can be performed with high reliability. Mercury(II) salts equilibrate the Z- and E-bromo enol lactones, presumedly by a mercuric ion addition-elimination mechanism. These three reactions provide access to an array of stereoisomeric bromo enol lactone systems.