Bicyclo[6.3.0]undecapentaenyl Anion: The Next Higher Homolog of Indenyl Anion with Exceptionally Large Ion-Pairing Effects on its Tropicity
Bicyclo[6.3.0]undecapentaenyl Anion: The Next Higher Homolog of Indenyl Anion with Exceptionally Large Ion-Pairing Effects on its Tropicity
复制标题
双环[6.3.0]十一五烯基阴离子：茚基阴离子的下一个更高同系物，对其热带性具有异常大的离子对影响
DOI：
10.1002/asia.201301307
复制
发表时间：
2014
影响因子：
4.1
通讯作者：
Takeshi Kawase
中科院分区：
文献类型：
--
作者：
Hiroaki Ozoe;Yasutaka Uno;Chitoshi Kitamura;Hiroyuki Kurata;Masaji Oda;John W. Jones;Jr.;Lawrence T. Scott;Takeshi Kawase
在四氢呋喃（THF）和二甲亚砜（DMSO）中，通过几种碱（氢化钠、氢化钾、二异丙基氨基锂和六甲基二硅氮基锂）与适当的双环[6.3.0]十一碳五烯作用，生成了热稳定的标题阴离子1。[D8]THF中1 Li+的变温1H NMR光谱表明，阴离子表现出异常大的离子配对效应;质子化学位移随离子配对条件的变化超过1 ppm。 因此，阴离子1，在接触离子对（Li+在环境温度下在THF中），表现为芳香族双阴离子，仅轻微地受到顺磁性环辛四烯（COT）的电子效应的干扰，而1在分离的离子对（Li+在低温下在THF中或在环境温度下在DMSO中）表现为具有12 π电子外围的整体paratropic物种。13 C NMR光谱表明没有主要的骨架重排，只有电子密度的微小变化。 1的可变的向性可归因于分子的小的构象变化。除了其不寻常的、可调的向性外，阴离子1还可以作为合成与完全不饱和八元环稠合的环戊烷共轭体系的通用构建单元。理论计算预测1的10位应该具有最高的电子密度。与这一预测一致，1与亲电子试剂的反应主要发生在10-位置。通过1与适当的亲电试剂反应，得到了相应的二茂铁、两个富烯、两个重氮衍生物和一个COT稠合的甘菊环。
The title anion1was generated as a fairly thermally stable species in tetrahydrofuran (THF) and dimethylsulfoxide (DMSO) by the action of several bases (sodium hydride, potassium hydride, lithium diisopropylamide, and lithium hexamethyldisilazide) with appropriate bicyclo[6.3.0]undecapentaenes. Variable‐temperature1H NMR spectra of1⋅Li+in [D8]THF reveal that the anion exhibits exceptionally large ion‐pairing effects; proton chemical shifts vary by more than 1 ppm as a function of ion‐pairing conditions. Thus, anion1, in a contact ion pair (Li+at ambient temperature in THF), behaves as an aromatic cyclopentadienyl anion that is perturbed only slightly by the electronic effects of a paramagnetic cyclooctatetraene (COT), whereas1in a separated ion pair (Li+at low temperatures in THF or at ambient temperature in DMSO) behaves as an overall paratropic species with a 12 π‐electron periphery.13C NMR spectroscopy indicates no major skeletal rearrangement and only small variations of the electron density. The variable tropicity of1can be ascribed to small conformational changes of the molecule. In addition to its unusual, tunable tropicity, anion1can also serve as a versatile building block for the synthesis of cyclopentanoid conjugated systems fused to a fully unsaturated eight‐membered ring. A theoretical calculation predicts that the 10‐position of1should have the highest electron density. In agreement with this prediction, the reactions of1with electrophiles occur predominantly at the 10‐position. The corresponding ferrocene, two fulvenes, two diazo derivatives, and a COT‐fused azulene were obtained by the reactions of1with appropriate electrophiles.