A Scalable and Expedient Route to 1-Aza[6]helicene Derivatives and Its Subsequent Application to a Chiral-Relay Asymmetric Strategy
摘要:
A rapid route to diversely functionalized 1-aza[6]helicenes has been achieved via the development of a copper-mediated cross-coupling reaction, followed by PtCl4-catalyzed cycloisomerization. Not only does this method allow access to these functionally important molecules on gram scale, but this strategy Is also suitable for relaying the axial chirality of a key intermediate to the helicity of the product.
Attenuation of London Dispersion in Dichloromethane Solutions
作者:Robert Pollice、Marek Bot、Ilia J. Kobylianskii、Ilya Shenderovich、Peter Chen
DOI:10.1021/jacs.7b06997
日期:2017.9.20
Londondispersion constitutes one of the fundamental interaction forces between atoms and between molecules. While modern computational methods have been developed to describe the strength of dispersive interactions in the gas phase properly, the importance of inter- and intramolecular dispersion in solution remains yet to be fully understood because experimental data are still sparse in that regard
importance of London dispersion for structure and stability of molecules with less than about 200 atoms has been established in recent years but the quantitative understanding is still largely based on computations because of a persistent lack of suitable experimental data. We herein report a comprehensive computational and experimental study of the compensation of London dispersion in proton-bound dimer
Intense redox-driven chiroptical switching with a 580 mV hysteresis actuated through reversible dimerization of an azoniahelicene
作者:Jochen R. Brandt、Lubomír Pospíšil、Lucie Bednárová、Rosenildo Correa da Costa、Andrew J. P. White、Tadashi Mori、Filip Teplý、Matthew J. Fuchter
DOI:10.1039/c7cc04903j
日期:——
we present the first intermolecular follow-on reaction: an azoniahelicene system that dimerises upon reduction, leading to intense, reversible chiroptical switching with a >500 mV hysteresis and a >300 mV “read-only” potential range. The reported helicene dimerization is supported by detailed electrochemical investigations and the comparison of experimental and calculated electronic circular dichroism
chirality of the helicenes while the sign of the latter is susceptive to the various factors such as electronic and steric effects. Protonation to monoaza[6]helicenes produces azonia[6]helicenes, showing dramatic changes in the CE pattern from the two bisignate to a three positive, two negative CE extremum series of comparable magnitudes, while dual protonation to diaza[6]helicenes forming diazonia[6]helicenes
结合实验和理论研究,揭示了单和重氮[6]螺旋的特征圆二色性(CD)光谱图,这与母体[6]螺旋烯和中性(di)氮杂类似物的报道有明显不同。Aza [6]螺旋和[6]螺旋烯在1 B a和1 B b波段表现出双信号棉花效应(CEs),在1 L b表现出弱CE。螺旋带,前者的信号负责螺旋的螺旋手性,而后者的信号易受电子和空间效应等各种因素的影响。质子化成单氮杂[6]螺旋的质子产生了氮杂[6]螺旋,显示出CE模式从两个二元组到三个正,两个负的CE极值级列具有相似程度的剧烈变化,而重质子化成重氮[6]螺旋的二元质子形成了重氮。 [6]螺旋在CE模式中仅导致名义变化(旋转强度和激发能稍有不同)。单氮杂二酮和重氮杂戊酮的这种相当复杂和相反的CE行为主要来自(非对称)质子化的电子效应,因为中性,单氮杂,和专用物种在本质上是彼此相同的。与中性(di)aza [6]螺旋油相比,通过最新的RI-CC2 / TZVPP
A Straightforward Route to Helically Chiral N-Heteroaromatic Compounds: Practical Synthesis of Racemic 1,14-Diaza[5]helicene and Optically Pure 1- and 2-Aza[6]helicenes
作者:Jiří Míšek、Filip Teplý、Irena G. Stará、Miloš Tichý、David Šaman、Ivana Císařová、Pavel Vojtíšek、Ivo Starý