2-hydroxy-2-(2',4',6'-trimethylphenyl)-5,7-dimethyl-1-indanone

• 分子结构分类: 有机化合物 - 苯类化合物 - 茚满类
• 英文名称: 2-hydroxy-2-(2',4',6'-trimethylphenyl)-5,7-dimethyl-1-indanone
• 英文别名: 2-hydroxy-5,7-dimethyl-2-(2,4,6-trimethylphenyl)-3H-inden-1-one
• 化学式: C₂₀H₂₂O₂
• 分子量: 294.393
• InChiKey: RLAYLYZRYMPUHN-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  4.4
• 重原子数：
  22
• 可旋转键数：
  1
• 环数：
  3.0
• sp3杂化的碳原子比例：
  0.35
• 拓扑面积：
  37.3
• 氢给体数：
  1
• 氢受体数：
  2

反应信息

• 作为产物：
  描述：

  mesitil 以 苯 为溶剂， 生成 2-hydroxy-2-(2',4',6'-trimethylphenyl)-5,7-dimethyl-1-indanone
  参考文献：
  名称：

  Photocyclization of 2,4,6,2',4',6'-Hexaalkylbenzils

  摘要：

  Three of the title compounds-the hexamethyl-, hexaethyl-, and hexaisopropylbenzils-all photocyclize both in solution and as solids to 5,7-dialkyl-2-(2',4',6'-trialkylphenyl)-2-hyudroxy-1-indanones. At wavelengths <370 nm these primary photoproducts undergo secondary photocleavage to ketoaldehydes. The hexaethylbenzil produces only the (Z)-hydroxyindanone in the solid but a 2/1 Z/E ratio at low conversion in solution. The solid-state reactivity and the preference for formation of the (Z)-hydroxyindanone from the hexaethylbenzil suggest that much of the reaction involves delta-hydrogen abstraction followed by coupling of the 1,5-biradical. The formation of (E)-hydroxyindanones from o-ethylphenyl diketones had been attributed to stereospecific rearrangement of a photodienol formed by gamma-hydrogen abstraction. However, none of the H/D exchange of benzylic hydrogens expected of a photodienol occurs in methanol-d(4). Moreover, AM1-level semiempirical calculations suggest that a simple exothermic hydrogen transfer can convert the 1,4-biradical tripler dienol to the same 1,5-biradical formed by delta-hydrogen abstraction. The 1,5-biradical has two major conformations, one leading to Z product and an internally OH-O=C hydrogen bonded one leading to E product. The AM1 computations suggest that the two conformations are of comparable energy and thus implicate 1,5-biradicals as the major precursors to hydroxyindanone products. Stem-Volmer quenching studies indicate a triplet decay rate of 5 x 10(6) s(-1) for the hexaisopropylbenzil. The known behavior of structurally similar monoketones predicts such a rate for delta-hydrogen abstraction but a much slower rate for gamma-hydrogen abstraction. However, relative quantum efficiencies parallel those for benzocyclobutenol formation from 2,4,6-trialkylbenzophenones (iPr and Et similar to 0.3, Me similar to 0.03). The hexa-tert-butylbenzil undergoes very low quantum yield formation of 3,3-dimethyl-5,7-di-tert-butyl-1-indanone and 2,4,6-tri-tert-butylbenzaldehyde, presumably by delta-hydrogen abstraction and highly efficient radical cleavage of the resulting 1-aroyl-1-indanol.

  DOI：

  10.1021/ja00134a006

文献信息

• Photocyclization of 2,4,6,2',4',6'-Hexaalkylbenzils
  作者：Peter J. Wagner、Bong-Ser Park、Martin Sobczak、Joseph Frey、Zvi Rappoport

  DOI：10.1021/ja00134a006

  日期：1995.7

  Three of the title compounds-the hexamethyl-, hexaethyl-, and hexaisopropylbenzils-all photocyclize both in solution and as solids to 5,7-dialkyl-2-(2',4',6'-trialkylphenyl)-2-hyudroxy-1-indanones. At wavelengths <370 nm these primary photoproducts undergo secondary photocleavage to ketoaldehydes. The hexaethylbenzil produces only the (Z)-hydroxyindanone in the solid but a 2/1 Z/E ratio at low conversion in solution. The solid-state reactivity and the preference for formation of the (Z)-hydroxyindanone from the hexaethylbenzil suggest that much of the reaction involves delta-hydrogen abstraction followed by coupling of the 1,5-biradical. The formation of (E)-hydroxyindanones from o-ethylphenyl diketones had been attributed to stereospecific rearrangement of a photodienol formed by gamma-hydrogen abstraction. However, none of the H/D exchange of benzylic hydrogens expected of a photodienol occurs in methanol-d(4). Moreover, AM1-level semiempirical calculations suggest that a simple exothermic hydrogen transfer can convert the 1,4-biradical tripler dienol to the same 1,5-biradical formed by delta-hydrogen abstraction. The 1,5-biradical has two major conformations, one leading to Z product and an internally OH-O=C hydrogen bonded one leading to E product. The AM1 computations suggest that the two conformations are of comparable energy and thus implicate 1,5-biradicals as the major precursors to hydroxyindanone products. Stem-Volmer quenching studies indicate a triplet decay rate of 5 x 10(6) s(-1) for the hexaisopropylbenzil. The known behavior of structurally similar monoketones predicts such a rate for delta-hydrogen abstraction but a much slower rate for gamma-hydrogen abstraction. However, relative quantum efficiencies parallel those for benzocyclobutenol formation from 2,4,6-trialkylbenzophenones (iPr and Et similar to 0.3, Me similar to 0.03). The hexa-tert-butylbenzil undergoes very low quantum yield formation of 3,3-dimethyl-5,7-di-tert-butyl-1-indanone and 2,4,6-tri-tert-butylbenzaldehyde, presumably by delta-hydrogen abstraction and highly efficient radical cleavage of the resulting 1-aroyl-1-indanol.