2,4-Bis(4-methoxyphenyl)cyclobutane-1,3-dione | 51673-49-5

• 分子结构分类: 有机化合物 - 苯类化合物 - 苯酚醚
• 英文名称: 2,4-Bis(4-methoxyphenyl)cyclobutane-1,3-dione
• CAS: 51673-49-5
• 化学式: C₁₈H₁₆O₄
• 分子量: 296.323
• InChiKey: RYSQEFFKBTXCKV-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  3.2
• 重原子数：
  22
• 可旋转键数：
  4
• 环数：
  3.0
• sp3杂化的碳原子比例：
  0.22
• 拓扑面积：
  52.6
• 氢给体数：
  0
• 氢受体数：
  4

反应信息

• 作为反应物：
  描述：

  Isophthalamide anthracene macrocycle 、 2,4-Bis(4-methoxyphenyl)cyclobutane-1,3-dione 以 氯仿 为溶剂， 反应 0.08h， 以100%的产率得到
  参考文献：
  名称：

  Internal and External Stereoisomers of Squaraine Rotaxane Endoperoxide: Synthesis, Chemical Differences, and Structural Revision

  摘要：

  Photooxygenation of permanently interlocked squaraine rotaxanes with anthracene-containing macrocydes produces the corresponding squaraine rotaxane endoperoxides (SREPs) quantitatively. SREPs are stored at low temperature, and upon warming, they undergo clean cycloreversion, releasing singlet oxygen and emitting light. The structural elucidation in 2010 assigned the structure as the SREP-int stereoisomer, with the endoperoxide unit directed inside the macrocycle cavity. New experimental and computational evidence reported here proves that the initial, kinetic photooxygenation product is the less stable SREP-ext stereoisomer with the endoperoxide unit directed outside the macrocycle. The photophysical properties and subsequent reactivity of mechanically strained SREP-ext depend on the size of the end groups of the encapsulated squaraine dye. If the end groups are sufficiently large to prevent dissociation of the interlocked components, the strained SREP-ext stereoisomer undergoes clean, thermal cycloreversion. However, smaller squaraine end groups allow transient dissociation, resulting in a pseudorotaxane dissociation/association process that produces SREP-int as the thermodynamic stereoisomer that does not cyclorevert. The large difference in endoperoxide reactivity for the two SREP stereoisomers illustrates the power of the mechanical bond to induce cross-component steric strain and selective enhancement of a specific reaction pathway. The new insight enabled synthetic development of triptycene-containing squaraine rotaxanes with high fluorescence quantum yields and large Stokes shifts.

  DOI：

  10.1021/jo402564k