Electroreductive Radical Borylation of Unactivated (Hetero)Aryl Chlorides Without Light by Using Cumulene‐Based Redox Mediators**
摘要:
摘要单电子转移(SET)在从有机合成到环境修复的许多化学过程中发挥着关键作用。然而,选择性还原惰性底物(Ep/2<-2 V vs Fc/Fc+),如无处不在的电子中性和电子丰富的(杂)芳基氯化物,仍然是一项重大挑战。目前的方法主要依赖催化剂的光激发来达到必要的深度还原电位,或者受限于底物范围。在此,我们证明了积雪烯--具有多个连续双键的有机分子--可以作为催化氧化还原介质,在相对温和的阴极电位(相对于 Ag/AgCl 约为 -1.9 V)下催化(杂)芳基氯的电还原自由基硼烷基化,而无需光辐射。电化学、光谱和计算研究证明,电子从还原型积雪烯逐步转移到电子中性的氯烯烃后,芳基自由基阴离子会发生热力学上有利的介解裂解,生成所需的芳基自由基中间体。我们的发现将为利用有机氧化还原介质对惰性分子进行其他可持续的纯电导自由基转化提供指导。
Mechanosynthesis of Odd‐Numbered Tetraaryl[
<i>n</i>
]cumulenes
作者:Karen J. Ardila‐Fierro、Carsten Bolm、José G. Hernández
DOI:10.1002/anie.201905670
日期:2019.9.9
A mechanochemical synthesis of one‐dimensional carbon allotrope carbyne model compounds, namely tetraaryl[n]cumulenes (n=3, 5) was realized. Central for the mechanosynthesis of the cumulenic carbon nanostructures were the development of a mechanochemical Favorskii alkynylation‐type reaction and the implementation of a solvent‐free, acid‐free reductive elimination with tin(II) chloride by ball milling
实现了一维碳同素异形体碳炔模型化合物,即四芳基[ n ]累积烯(n =3, 5)的机械化学合成。积碳碳纳米结构机械合成的核心是机械化学 Favorskii 炔基化反应的发展,以及通过球磨实现无溶剂、无酸的氯化锡 (II) 还原消除。
Thermal cyclotrimerization of tetraphenyl[5]cumulene(tetraphenylhexapentaene) to a tricyclodecadiene derivative
Tetraphenyl[5]cumulene (tetraphenylhexapentaene) underwent cyclotrimerization in refluxing toluene for 10–15 min to give a tricyclodecadiene derivative in 68% yield.
chlorotris(triphenylphosphine) rhodium produces a red complex in which rhodium is bound to the second CC bond of the cumulene. In contrast, reaction of the same cumulene with (PPh3)2Pt0 generated by reducing (PPh3)2PtCl2 with hydrazine in ethanol results in the formation of a yellow symmetrical complex as the kinetic product. This complex isomerizes to a red unsymmetrical complex. An X-ray crystal structure
A novel CC bond cleavage in hexacarbonyl(hexapentaene)diiron: X-ray crystal structure of a bis(µ<sub>3</sub>,η<sup>2</sup>-allenylidene)–iron complex
作者:Masahiko Iyoda、Yoshiyuki Kuwatani、Masaji Oda
DOI:10.1039/c39920000399
日期:——
Aryl-substituted hexacarbonyl(hexapentaene)diironcomplexes undergo facile intramolecular CC bond cleavage on treatment with [Fe3(CO)12] to yield the corresponding bis(µ3,η2-allenylidene)–iron complexes; the X-ray crystal structures of phenyl-substituted bis(µ3,η2-allenylidene)–iron and related allenylidene complexes are determined.
A New Preparative Method of Buta-1,3-diene and Hexa-1,5-dien-3-yne by Reduction of Butatriene and Hexapentaene, Respectively, with Zn–ZnCl<sub>2</sub>-H<sub>2</sub>O
作者:Satoshi Kishigami、Koichi Tanaka、Fumio Toda
DOI:10.1246/cl.1990.1877
日期:1990.10
The Zn–ZnCl2–H2O reagent was found to be effective for the reduction of aryl group substituted butatrienes and hexapentaenes to buta-1,3-dienes and hexa-1,5-dien-3-ynes, respectively.