Chaolumen, Hideto Ito,* Kenichiro Itami*
Chem. Commun. 2019, 55, 9606-9609 . DOI: 10.1039/C9CC03510A
Selected as a front cover in volume 55, issume 65.

[軸不斉π拡張ビアズレンの合成]

近年、ヘリセンのように縮環したキラルなπ共役化合物の合成や物性に興味が持たれている。今回我々は、軸不斉をもつ種々の1,1′-ビアズレン誘導体の合成に成功した。terphenyl基をもつアズレンを出発原料とし、FeCl₃で段階的に処理するだけで2,2′-diterphenyl-1,1′-biazuleneとそのπ拡張体を合成した。合成した1,1′-ビアズレン誘導体は軸不斉をもち、キラルカラムでエナンチオマーを容易に分離可能であった。さらに、各種分光学的解析やX線結晶構造解析によってその構造と光物性を明らかにした。

[Axially chiral π-extended biazulenes]

Chiral organic π-conjugated molecules have been intensively investigated in the fields of chiral electronic materials and devices. Herein we report a new motif for an axially chiral 1,1′-biazulene and its π-extended derivative, in which biphenyl was annulated by the electron-rich five-membered-ring of the azulene moiety. These two compounds were unexpectedly synthesized from 2-terphenyl azulene by stepwise intermolecular and intramolecular oxidative C–H/C–H couplings. X-ray diffraction analysis revealed that the crystals of both compounds contain a pair of enantiomers. Furthermore, the axially chiral 1,1′-biazulene derivatives were successfully separated into enantiomers that exhibited clear mirror-image circular dichroism spectra up to the near-infrared region.