4,4,5,5-tetramethyl-2-[(3E,5E)-2,2,7,7-tetramethyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)octa-3,5-dien-4-yl]-1,3,2-dioxaborolane | 178693-07-7

• 分子结构分类: 有机化合物 - 有机酸及其衍生物 - 硼酸衍生物
• 英文名称: 4,4,5,5-tetramethyl-2-[(3E,5E)-2,2,7,7-tetramethyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)octa-3,5-dien-4-yl]-1,3,2-dioxaborolane
• CAS: 178693-07-7
• 化学式: C₂₄H₄₄B₂O₄
• 分子量: 418.233
• InChiKey: WOCBDECVUYEFJF-IQRFGFHNSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  6.19
• 重原子数：
  30
• 可旋转键数：
  5
• 环数：
  2.0
• sp3杂化的碳原子比例：
  0.83
• 拓扑面积：
  36.9
• 氢给体数：
  0
• 氢受体数：
  4

反应信息

• 作为产物：
  描述：

  2-(3,3-dimethylbut-1-yn-1-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 在 HZrCp₂Cl 、 CuBr 、 NH₄Cl 作用下， 以 四氢呋喃 、 水 为溶剂， 以59%的产率得到4,4,5,5-tetramethyl-2-[(3E,5E)-2,2,7,7-tetramethyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)octa-3,5-dien-4-yl]-1,3,2-dioxaborolane
  参考文献：
  名称：

  Zirconocene-Mediated Preparation of 1,3-, 1,4-, and 2,3-Dibora-1,3-butadienes:  Their Isolation and Characterization and Use in Suzuki−Miyaura Coupling

  摘要：

  Hydrozirconation of 1-alkynyl pinacolboronates, 1, with HZrCp(2)Cl provides gem-borazirconocenes 2. The latter when treated with CuBr gives the homocoupled (1E,3E)-2,3-dibora-1,3-butadienes, 3, in good yield (62-67%). The reaction works even for hindered 2 (R = t-Bu). Structure 3 was assigned on the basis of NMR. Suzuki-Miyaura coupling of 3a (R = n-Bu) with PhI in the presence of CsF leads to the replacement of both boron groups by phenyl and hydrogen to give 6 in 76% yield. Zirconocene-mediated coupling of 1 leads to diastereomeric products: (1E,3E)-1,3-dibora-1,3-butadienes, 4, in 7-26% isolated yields and (1E,3E)-1,4-dibora-1,3-butadienes, 5, in 17-34% isolated yields. The two isomers can be separated by selective precipitation of 5 from the reaction mixture in pentane (-20 degrees C) followed by silica gel chromatography to give pure 4. The reaction does not work when R in 1 is the t-Bu group. Assignments of structures for 4 and 5 were done on the basis of 1D and 2D NMR experiments. In addition, a single-crystal X-ray analysis of 5a showed it to be a highly planar and linearly oriented molecule. Suzuki-Miyaura coupling of 4a proceeded to replace the terminal boron group exclusively, while the internal boron group of 4a remained intact.

  DOI：

  10.1021/om960178n