2,2-Dimethyl-1,3-bis(4'-nitrophenyl)-1,3-propanedione | 155886-77-4

• 分子结构分类: 有机化合物 - 苯丙烷和聚酮 - 直链 1,3-二芳基丙烷
• 英文名称: 2,2-Dimethyl-1,3-bis(4'-nitrophenyl)-1,3-propanedione
• 英文别名: 2,2-Dimethyl-1,3-bis(4-nitrophenyl)propane-1,3-dione
• CAS: 155886-77-4
• 化学式: C₁₇H₁₄N₂O₆
• 分子量: 342.308
• InChiKey: FFEULJMAJCSASR-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  3.7
• 重原子数：
  25
• 可旋转键数：
  4
• 环数：
  2.0
• sp3杂化的碳原子比例：
  0.18
• 拓扑面积：
  126
• 氢给体数：
  0
• 氢受体数：
  6

反应信息

• 作为反应物：
  描述：

  2,2-Dimethyl-1,3-bis(4'-nitrophenyl)-1,3-propanedione 在 一水合肼 、 三氟乙酸 作用下， 以 氘代氯仿 、 二氯甲烷 、 氯仿 为溶剂， 反应 6.33h， 生成 4,4-Dimethyl-3,5-bis(4'-nitrophenyl)-4H-pyrazole
  参考文献：
  名称：

  Electronic Substituent Effects on the Acid-Catalyzed [4+ + 2] Cycloaddition of Isopyrazoles with Cyclopentadiene and the Photochemical and Thermal Denitrogenation of the Resulting 1,4-Diaryl-7,7-dimethyl-2,3-diazabicyclo[2.2.1]hept-2-ene Azoalkanes to Bicyclo[2.1.0]pentanes

  摘要：

  Eight symmetrically disubstituted 3,5-diaryl-4,4-dimethylisopyrazoles 6 with para and meta substituents (OMe, Me, H, F, Cl, Br, CN, NO2) and two unsymmetrically para-substituted derivatives (OMe and NO2; Me and CO(2)Me) were synthesized from the corresponding 1,3-diaryl-2,2-dimethyl-1,3-propanediones 5, which in turn were readily available by 2,2-dimethylation of the diones 4. The acid-catalyzed cycloaddition of cyclopentadiene to the isopyrazoles 6, a Diels-Alder reaction with inverse electron demand, afforded the 1,4-diaryl-substituted gem-dimethyl azoalkanes 7 of the diazabicyco[2.2.1]hept-2-ene (DBH) type. The cycloadduct yields were strongly dependent on the nature of the aryl substituents and highest for the electron-withdrawing substituents. In acidic solution, the azoalkanes showed cycloreversion to generate an equilibrium between isopyrazole 6, cyclopentadiene, and azoalkane 7. For the p-methoxy derivative, cycloreversion was essentially quantitative, whereas only 20% cycloreversion occurred for the para nitro compound. A positive Hammett rho value (rho = 3.24 for 2 equiv of CF3COOH) was determined for the equilibrium constants of the acid-catalyzed [4(+) + 2] cycloaddition. The unsymmetrically substituted isopyrazoles gave two regioisomeric cycloadducts with a slight excess of one isomer. The direct and triplet-sensitized photochemical and thermal denitrogenation of the azoalkanes 7 gave in quantitative yields the 1,4-diaryl-substituted bicyclo[2.1.0]pentanes (BCP) 8 with retention of configuration. The azoalkanes 7 and the housanes 8 are more persistent than the related 1,4-diaryl-substituted DBH and BCP derivatives. The stabilizing effect is rationalized in terms of less favorable benzylic conjugation in the transition states for C-N (azoalkanes) and C-C (housanes) bond cleavage due to steric interactions between the geminal methyl groups at the methane bridge and the diaryl substituents at the bridgehead sites.

  DOI：

  10.1021/jo00093a010
• 作为产物：
  描述：

  1,3-bis-(4-nitrophenyl)propane-1,3-dione 、 碘甲烷 在 potassium carbonate 作用下， 以 氯仿 、 二甲基亚砜 为溶剂， 以34%的产率得到2,2-Dimethyl-1,3-bis(4'-nitrophenyl)-1,3-propanedione
  参考文献：
  名称：

  Electronic Substituent Effects on the Acid-Catalyzed [4+ + 2] Cycloaddition of Isopyrazoles with Cyclopentadiene and the Photochemical and Thermal Denitrogenation of the Resulting 1,4-Diaryl-7,7-dimethyl-2,3-diazabicyclo[2.2.1]hept-2-ene Azoalkanes to Bicyclo[2.1.0]pentanes

  摘要：

  Eight symmetrically disubstituted 3,5-diaryl-4,4-dimethylisopyrazoles 6 with para and meta substituents (OMe, Me, H, F, Cl, Br, CN, NO2) and two unsymmetrically para-substituted derivatives (OMe and NO2; Me and CO(2)Me) were synthesized from the corresponding 1,3-diaryl-2,2-dimethyl-1,3-propanediones 5, which in turn were readily available by 2,2-dimethylation of the diones 4. The acid-catalyzed cycloaddition of cyclopentadiene to the isopyrazoles 6, a Diels-Alder reaction with inverse electron demand, afforded the 1,4-diaryl-substituted gem-dimethyl azoalkanes 7 of the diazabicyco[2.2.1]hept-2-ene (DBH) type. The cycloadduct yields were strongly dependent on the nature of the aryl substituents and highest for the electron-withdrawing substituents. In acidic solution, the azoalkanes showed cycloreversion to generate an equilibrium between isopyrazole 6, cyclopentadiene, and azoalkane 7. For the p-methoxy derivative, cycloreversion was essentially quantitative, whereas only 20% cycloreversion occurred for the para nitro compound. A positive Hammett rho value (rho = 3.24 for 2 equiv of CF3COOH) was determined for the equilibrium constants of the acid-catalyzed [4(+) + 2] cycloaddition. The unsymmetrically substituted isopyrazoles gave two regioisomeric cycloadducts with a slight excess of one isomer. The direct and triplet-sensitized photochemical and thermal denitrogenation of the azoalkanes 7 gave in quantitative yields the 1,4-diaryl-substituted bicyclo[2.1.0]pentanes (BCP) 8 with retention of configuration. The azoalkanes 7 and the housanes 8 are more persistent than the related 1,4-diaryl-substituted DBH and BCP derivatives. The stabilizing effect is rationalized in terms of less favorable benzylic conjugation in the transition states for C-N (azoalkanes) and C-C (housanes) bond cleavage due to steric interactions between the geminal methyl groups at the methane bridge and the diaryl substituents at the bridgehead sites.

  DOI：

  10.1021/jo00093a010

文献信息

• Radical Stabilization and Ground State Polar Substituent Effects in the Thermal Decomposition of Azoalkanes
  作者：Werner M. Nau、Heinrich M. Harrer、Waldemar Adam

  DOI：10.1021/ja00103a012

  日期：1994.11

  The thermolysis rates of a series of the 1,4-diaryl-2,3-diaza[2.2.1]bicyclohept-2 derivatives 1 with a large variety of aryl substituents (p-NH2, p-OMe, p-Me, H, p-F, p-Cl, p-Br, m-I, p-I, Nt-CN, p-CN, m-NO2, p-NOz, and p-CO(2)Me) have been determined to probe the electronic substituent effects in the thermal decomposition of azoalkanes. The correlation of the logarithmic relative rate constants versus the Creary substituent constants for radical stabilization (cf. Creary, X.; et al. J. Org. Chem. 1987, 52, 3254) improved considerably when polar effects (positive rho value) were included in the form of a two-parameter Hammett treatment. The importance of polar effects was also established in the reported thermolysis rate data for aryl-substituted azopropanes 2, azoethanes 3, azomethanes 4, azoneopentanes 5, and 3,5-diaryl-1-pyrazolines 6. The two-parameter analysis reveals that the thermal decomposition rates of azoalkanes are enhanced by radical- as well as anion-stabilizing substituents. On one hand, the ratio of the radical and polar reaction constants (rho(rad)+rho(pol)) serves as useful parameter to diagnose the radical nature in the decompositions of azoalkanes; thus, in general, radical effects dominate within the azoalkane 1-6 series. On the other hand, the overall sensitivity of the thermal decompositions toward substituent effects is reflected by the sum of the reaction constants (rho(rad)+rho(pol)) The polar effect is attributed to polar destabilization in the ground states of the azoalkanes, for which the polarized C-N bond is weakened by aryl substituents with electron accepters at the positively charged benzylic carbon atom. Semiempirical (AM1) calculations corroborate such polar effects for the azoalkanes 1-6 versus their corresponding diaryl-substituted alkanes 7-12.