Rhenium-Catalyzed [4 + 1] Annulation of Azobenzenes and Aldehydes via Isolable Cyclic Rhenium(I) Complexes
作者:Xiaoyu Geng、Congyang Wang
DOI:10.1021/acs.orglett.5b00938
日期:2015.5.15
The first Re-catalyzed [4 + 1] annulation of azobenzenes with aldehydes was developed to furnish 2H-indazoles via isolable and characterized cyclic ReI-complexes. For the first time, the acetate-acceleration effect is showcased in Re-catalyzed C–H activation reactions. Remarkably, mechanistic studies revealed an irreversible aldehyde-insertion step, which is in sharp contrast to those of previous Rh-
Palladium-Catalyzed Oxidative Synthesis of Unsymmetrical Azophenols
作者:Thi Hong Long Nguyen、Nicolas Gigant、Sandrine Delarue-Cochin、Delphine Joseph
DOI:10.1021/acs.joc.5b02614
日期:2016.3.4
reported. The developed methodology tolerates various functional groups and allows the synthesis of diverse unsymmetrical azophenols under mild conditions in good to excellent yields. A complementary procedure was also investigated by in situ generation of PIFA. This study represents the first general method for the synthesis of o-hydroxyazobenzenes starting from simple azoarenes.
molybdenum oxide compound, [N(C4H9)4]2[Mo6O19] (1), catalyzed selective oxidation of anilines with hydrogen peroxide as green oxidant. The oxidation of anilines can be realized in a fully selectively fashion to afford various symmetric/asymmetric azobenzene and azoxybenzene compounds, respectively, by changing additive and solvent, avoiding the use of stoichiometric metal oxidants. Preliminary mechanistic
在医药和工业应用中起重要作用的芳族偶氮化合物在合成中仍然面临巨大挑战。在此,我们报道了一种氧化钼化合物[N(C 4 H 9)4 ] 2 [Mo 6 O 19 ](1),用过氧化氢作为绿色氧化剂催化苯胺的选择性氧化。苯胺的氧化可以完全选择性地实现,通过改变添加剂和溶剂避免使用化学计量的金属氧化剂,从而分别提供各种对称/不对称的偶氮苯和and氧基苯化合物。初步的机理研究表明,高活性的反应性和难以捉摸的钼亚胺配合物是中间的。
Study of Halogen-Mediated Weak Interactions in a Series of Halogen-Substituted Azobenzenes
作者:Maheswararao Karanam、Angshuman Roy Choudhury
DOI:10.1021/cg400967k
日期:2013.11.6
hydrogen bond lies in the range from −0.8 to −1.0 kcal/mol, while that for the C–X···X–C interaction has been found to be −0.35 kcal/mol for the X = Cl interaction and −0.73 kcal/mol for the X = Br interaction. Further, the analysis of these interaction by atoms in molecules (AIM) theory indicates that the electron densities (ρc) at the bond critical points (BCP) for C–H···F and C–X···X–C (X = Cl and Br)
photostationary state compositions that are not restricted to the spectral separation of the individual azobenzene isomers and their quantum yields. In addition, activating this radical isomerization pathway with photoelectron transfer agents allows us to override the intrinsic properties of an azobenzene species by triggering the reverse isomerization direction (Z → E) by the same wavelength of light,
合成了多种偶氮苯以研究其 E 和 Z 异构体在电化学还原时的行为。我们的结果表明,与中性物种相比,Z 异构体的自由基阴离子能够以显着提高的速率快速异构化为相应的 E 配置对应物。由于随后从形成的 E 自由基阴离子到中性 Z 起始材料的电子转移,整个转变在电子中是催化的;即,亚化学计量的还原物质可使整个混合物异构化。这种途径极大地提高了(光)转换的效率,同时还允许人们达到光稳定状态的组合物,该组合物不受单个偶氮苯异构体的光谱分离及其量子产率的限制。此外,用光电子转移剂激活这种自由基异构化途径使我们能够通过相同波长的光触发反向异构化方向 (Z → E) 来覆盖偶氮苯物种的固有特性,这通常会触发 E → Z 异构化。我们报告的行为似乎是普遍的,这意味着光开关的亚稳态异构体可以在还原时催化异构化为更稳定的异构体,从而允许以新的和间接的方式优化偶氮苯切换。