2-Bromo-5-methyl-5-(4-methylphenyl)-1,6-heptadiene | 171779-48-9

• 分子结构分类: 有机化合物 - 苯类化合物 - 苯和取代衍生物
• 英文名称: 2-Bromo-5-methyl-5-(4-methylphenyl)-1,6-heptadiene
• 英文别名: 1-(6-Bromo-3-methylhepta-1,6-dien-3-yl)-4-methylbenzene
• CAS: 171779-48-9
• 化学式: C₁₅H₁₉Br
• 分子量: 279.22
• InChiKey: YSMFGSVHUJSITF-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  5.6
• 重原子数：
  16
• 可旋转键数：
  5
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.33
• 拓扑面积：
  0
• 氢给体数：
  0
• 氢受体数：
  0

反应信息

• 作为反应物：
  描述：

  2-Bromo-5-methyl-5-(4-methylphenyl)-1,6-heptadiene 在 偶氮二异丁腈 、 三正丁基氢锡 作用下， 以 苯 为溶剂， 反应 2.5h， 以93%的产率得到4-Methyl-4-(4-methylphenyl)-1-methylenecyclohexane
  参考文献：
  名称：

  Conformational Control in the Cyclization of an Unsaturated Vinyllithium: Synthesis of (.+-.)-Laurene

  摘要：

  The olefinic vinyllithium 2, derived from 2-bromo-5-methyl-5-(4-methylphenyl)-1,6-heptadiene (3) by low-temperature lithium-bromine exchange, undergoes a diastereoselective B-exo cyclization at 0 degrees C in the presence of TMEDA to afford the naturally occurring sesquiterpene (+/-)-laurene (1) in 60% isolated yield along with 17% of the isomeric (+/-)-epilaurene (4). The diastereoselectivity of the cyclization of 2 is discussed in terms of a transition state for the process that approximates a chair cyclohexane which preferentially adopts a conformation having a pseudoaxial p-tolyl moiety and a pseudoequatorial methyl group at the geminally substituted carbon. In contrast to the behavior of 2, radical-mediated cyclization of 3 proceeds entirely in a 6-endo fashion to give 4-methyl-4-(4-methylphenyl)-1-methylenecyclohexan (6) in 93% yield.

  DOI：

  10.1021/jo00129a020
• 作为产物：
  描述：

  对甲基苯乙腈 在 四氯化钛 、 sodium hydride 、 lead(II) chloride 、 锌 作用下， 以 N,N-二甲基甲酰胺 为溶剂， 反应 37.0h， 生成 2-Bromo-5-methyl-5-(4-methylphenyl)-1,6-heptadiene
  参考文献：
  名称：

  Conformational Control in the Cyclization of an Unsaturated Vinyllithium: Synthesis of (.+-.)-Laurene

  摘要：

  The olefinic vinyllithium 2, derived from 2-bromo-5-methyl-5-(4-methylphenyl)-1,6-heptadiene (3) by low-temperature lithium-bromine exchange, undergoes a diastereoselective B-exo cyclization at 0 degrees C in the presence of TMEDA to afford the naturally occurring sesquiterpene (+/-)-laurene (1) in 60% isolated yield along with 17% of the isomeric (+/-)-epilaurene (4). The diastereoselectivity of the cyclization of 2 is discussed in terms of a transition state for the process that approximates a chair cyclohexane which preferentially adopts a conformation having a pseudoaxial p-tolyl moiety and a pseudoequatorial methyl group at the geminally substituted carbon. In contrast to the behavior of 2, radical-mediated cyclization of 3 proceeds entirely in a 6-endo fashion to give 4-methyl-4-(4-methylphenyl)-1-methylenecyclohexan (6) in 93% yield.

  DOI：

  10.1021/jo00129a020

文献信息

• Conformational Control in the Cyclization of an Unsaturated Vinyllithium: Synthesis of (.+-.)-Laurene
  作者：William F. Bailey、Xing-Long Jiang、Carla E. McLeod

  DOI：10.1021/jo00129a020

  日期：1995.12

  The olefinic vinyllithium 2, derived from 2-bromo-5-methyl-5-(4-methylphenyl)-1,6-heptadiene (3) by low-temperature lithium-bromine exchange, undergoes a diastereoselective B-exo cyclization at 0 degrees C in the presence of TMEDA to afford the naturally occurring sesquiterpene (+/-)-laurene (1) in 60% isolated yield along with 17% of the isomeric (+/-)-epilaurene (4). The diastereoselectivity of the cyclization of 2 is discussed in terms of a transition state for the process that approximates a chair cyclohexane which preferentially adopts a conformation having a pseudoaxial p-tolyl moiety and a pseudoequatorial methyl group at the geminally substituted carbon. In contrast to the behavior of 2, radical-mediated cyclization of 3 proceeds entirely in a 6-endo fashion to give 4-methyl-4-(4-methylphenyl)-1-methylenecyclohexan (6) in 93% yield.