Helicenes Fused with Hexafluorocyclopentene (HFCP): Synthesis, Structure, and Properties

Abstract

Helicenes fused with hexafluorocyclopentene (HFCP) were synthesized by oxidative photocyclization of stilbene derivatives (the Mallory reaction). Of the newly‐obtained fluorinated helicenes, the [7]helicenes bearing one‐ or three‐HFCP units were structurally characterized by X‐ray crystallographic analysis. The attempted synthesis of [9]helicene fused with three HFCP units resulted in the unexpected formation of a novel double helicene consisting of [4]‐ and [6]‐helicenes sharing peripheral benzene rings. Optical properties and chiral resolutions of the newly obtained HFCP‐substituted helicenes are also described.

Synthesis and photoluminescence properties of fluorine‐containing poly(phenylene vinylene) bearing hexafluorocyclopentene‐fused phenanthrene unit

“…Tetraethyl(2,5‐bis(dodecyloxy)‐1,4‐phenylene)bis(methylene)diphosphonate 21 and precursor 1 16 were prepared in 52% yield in accordance with the literature. The starting compounds for the synthesis of 1 , p ‐bromobenzaldehyle diethyl acetal and OFCP, were purchased and used without purification.…”

“…To a 200 mL Schlenk tube, toluene (150 mL) solution of precursor 1 16 (0.38 g, 1.0 mmol), 1,2‐epoxybutane (3.0 mL, 34 mmol) and iodine (0.060 g, 0.24 mmol) were added. After stirring at room temperature (RT) for 10 min, the reaction mixture was stirred further under light irradiation at RT for 15 h. During the light irradiation, iodine (0.25 g, 0.97 mmol) was added to the reaction mixture in four portions.…”

“…Recently, our group has found an efficient route to the synthesis of hexafluorocyclopentene (HFCP)-fused polycyclic aromatic hydrocarbons (PAHs), as illustrated in Scheme 1. [13][14][15][16] Octafluorocyclopentene (OFCP) is commercially available and is easy to handle and has high reactivity to various nucleophiles such as organolithium reagents to give the corresponding stilbene precursors (addition-defluorination). 17 The intramolecular photocyclization of a precursor in the presence of an oxidant irreversibly proceeds (Mallory reaction), [18][19][20] yielding the desired HFCP-fused PAH.…”

Synthesis, Photophysical and Electrochemical Study of 1,3,6,8‐Tetraarylsubstituted X‐Shaped Phenanthrene Derivatives

“…Phenanthrene has a curved structure that enables it to serve as a core building block for the synthesis of unique functional π-electron molecules such as conjugated macrocycles, [14][15][16][17][18] helicenes [19][20][21][22][23][24][25][26] and phenacenes. [27][28][29] Efforts have been con-ducted to extend the conjugation of phenanthrenes by introducing aryl substituents at 3-and 6-positions where its HOMO and LUMO orbital coefficients are large.…”

A General Synthetic Approach and Photophysical Properties of Regioselectively Fluorinated [5]‐ and [6]‐Helical Bispiroindenofluorenes

“…[1,2] A considerable attention has been payed to fluorinated aromatic and poly-aromatic compounds (PAHs) including fluorinated helicenes and these endeavors have been recently nicely summarized. [3,4] It should be mentioned that attaching of fluorine atoms to specific position of the polyaromatic scaffold (pinpoint-fluorinated polycyclic aromatic hydrocarbons -F-PAHs) is often a synthetic challenge and requires special approaches. [5][6][7] Interestingly, a very little attention has been payed to synthesis and property evaluation of other types of helical aromatic compounds with potential application in organic electronics such as fluorinated compounds possessing the dihydroindenofluorene scaffold.…”