Dihedral-Angle-Controlled Crossover from Static Hole Delocalization to Dynamic Hopping in Biaryl Cation Radicals
作者:Marat R. Talipov、Tushar S. Navale、Mohammad M. Hossain、Ruchi Shukla、Maxim V. Ivanov、Rajendra Rathore
DOI:10.1002/anie.201609695
日期:2017.1.2
In cases of coherent charge‐transfer mechanism in biaryl compounds the rates follow a squared cosine trend with varying dihedral angle. Herein we demonstrate using a series of biaryl cationradicals with varying dihedral angles that the hole stabilization shows two different regimes where the mechanism of the hole stabilization switches over from (static) delocalization over both aryl rings to (dynamic)
在联芳基化合物具有相干电荷转移机制的情况下,速率遵循具有二面角变化的余弦平方趋势。在本文中,我们证明了使用一系列具有不同二面角的联芳基阳离子自由基,空穴稳定化显示了两个不同的状态,其中空穴稳定化的机理从两个芳基环上的(静态)离域转换为(动态)跳跃。具有不同二面角的联芳烃的实验数据和DFT计算明确支持从离域到跳跃的交换发生在唯一的二面角处,其中电子耦合(H ab)是重组(λ)的一半,即H ab = λ/ 2。目前正在研究这一发现对非相干电荷传输速率的影响。
Gold(I)‐Catalyzed Intramolecular C(sp
<sup>3</sup>
)−H Insertion by Decarbenation of Cycloheptatrienes
作者:Xiang Yin、Giuseppe Zuccarello、Cristina García‐Morales、Antonio M. Echavarren
DOI:10.1002/chem.201900919
日期:2019.7.17
A novel synthesis of indanes and dihydronaphtalenes based on the intramolecular insertion into C(sp3)−H bonds of gold(I) carbenes generated by retro‐Buchner reaction (decarbenation) has been developed. Deuterium‐labeling and kinetic isotope effect experiments, DFTcalculations, and generation of the proposed carbene intermediate from a well‐characterized gold(I) carbenoid support the involvement of
Octahydro[1,4:5,8]dimethanoanthraquinone as a Cheap and Readily Available Electron-Transfer Oxidant for Biaryl Synthesis from Organocuprates
作者:Rajendra Rathore、Ruchi Shukla
DOI:10.1055/s-0028-1083232
日期:2008.12
The preparation of biaryls via oxidation of organocuprates with easily synthesized octahydro[1,4:5,8]dimethano-anthraquinone (DAQ) is described. The oxidative coupling of organocuprates using DAQ was successfully employed for the preparation of highly hindered biaryls and 9- and 10-membered macrocycles containing biaryl linkages. The oxidative reactivity of DAQ towards organocuprates is found to be similar
6-Alkyl derivatives of 3-(3,4-dihydroxyphenyl)alanine (dopa). Part I. Synthesis via oxazolinones
作者:A. P. Morgenstern、C. Schuijt、W. Th. Nauta
DOI:10.1039/j39710003706
日期:——
3-(3,4-Dihydroxyphenyl)alanines with a methyl, ethyl, or isopropyl group in the 6-position were obtained via the corresponding oxazolinones by an Erlenmeyer–Plöchl procedure. In the synthesis of 6-t-butyldopa (27) the intermediate α-benzamido-4,5-dimethoxy-2-t-butylcinnamic acid (21) was obtained in reasonable yield by treatment of the Grignard reagent from 5-t-butyl-4-bromoveratrole (11) with 4-e
Novel glycopeptide antibiotic derivatives. These derivatives are represented by the formula (aglycon part of glycopeptide antibiotic derivative)-(Sac-NH)—R
A
[wherein (aglycon part of glycopeptide antibiotic derivative) is the part formed by removing the sugar part from a known glycopeptide antibiotic derivative; (Sac-NH) part is an amino sugar part or a sugar chain part containing an amino sugar; and R
A
represents, e.g., the formula —X
1
—Ar
1
—X
2
—Y—X
3
—Ar
2
(wherein X
1
, X
2
, and X
3
each represents 1) a single bond or 2) a heteroatom or heteroatom-containing group selected from the group consisting of —N═, ═N—, —NR
1
—, —O—, etc.; Y represents —NR
2
CO— or —CONR
2
— (wherein R
2
represents hydrogen or lower alkyl), etc.)]. These derivatives have antibacterial activity against vancomycin-resistant bacteria.