Intermolecular Oxidative Annulation of 2‐Aminoanthracenes to Diazaacenes and Aza[7]helicenes

Abstract

Which way to go: The product distribution in the efficient oxidation of 2‐aminoanthracene derivatives to pyrazine‐ and pyrrole‐fused bisanthracenes can be controlled by additives (see scheme; TFA=trifluoroacetic acid, DDQ=2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone). The pyrrole‐fused dimer can be regarded as an aza[7]helicene with a stable helical conformation.

Circularly Polarized Luminescence from Simple Organic Molecules

“…38 CPL-SOM ( M )- and ( P )-18 exhibited complementary Vis circularly polarized fluorescence in CH 2 Cl 2 (| g lum | = 3·10 −3 , see Table 2) upon irradiation at 375 nm. 38 Also following the [7]helicene strategy, Nozaki and co-workers have reported complementary Vis circularly polarized fluorescence from both enantiomers of sila[7]helicene 19 (Figure 8; | g lum | = 3.5·10 −3 , upon UV irradiation in CH 2 Cl 2 ; see Table 2). 39 These CPL-SOMs were prepared by Pt-catalyzed double intramolecular hydroarylation of an achiral diyne precursor, followed by chiral-HPLC resolution of the obtained racemic mixture.…”

ChemInform Abstract: Circularly Polarized Luminescence from Simple Organic Molecules

“…[37b] In 2012, Shinokubo and co-workers obtaineda za[7]helicenes 18 (Figure 8) by oxidation of parent2 -aminoanthracene, followed by final chiral-HPLC resolution. [38] CPL-SOM (M)-and (P)-18 exhibited complementary Vis circularly polarized fluorescence in CH 2 Cl 2 (j g lum j = 310 À3 ,s ee Table 2) upon irradiation at 375 nm. [38] Also following the [7]helicene strategy,N ozaki and co-workers have reported complementary Vis circularly polarized fluorescence from both enantiomerso fs ila[7]helicene 19 (Figure8; Figure 6.…”

Phosphahelicenes: From Chiroptical and Photophysical Properties to OLED Applications

“…An appealing strategy to modify emission properties of helicenes consists in introducing heteroatom(s) or heterocycle(s) in the helical structure. For example, significant improvements of helicenes’ fluorescence properties have been recently achieved via introduction of such heterocycles as carbazole, maleimide, siloles, oxaborine, or azaborole . Among other possible heterocycles, the phosphole ring is an interesting subunit for tuning emission properties of helicenes since phosphole derivatives are known to be efficient fluorescent emitters for organic light‐emitting diodes (OLEDs) .…”