Synthesis of Polybenzoacenes: Annulative Dimerization of Phenylene Triflate by Twofold C−H Activation

Abstract

Polycyclic aromatic hydrocarbons (PAHs) represent an emerging class of π‐conjugated molecules in the area of optoelectronic devices and materials. Unprecedented synthetic routes to various PAHs from simple phenol derivatives by a palladium‐catalyzed annulative dimerization of phenylene triflate through twofold inter‐ and intramolecular C−H activation have been established. The initially formed partially fused PAHs can be smoothly transformed into a variety of fully fused PAHs by the Scholl reaction. Furthermore, the reactions of phenanthrene‐substituted aryl triflates proceeded regioselectively. The findings inspired the development of a rapid and efficient synthesis of polybenzoacene derivatives. This study not only allows transformation of phenyl triflates, but also discloses a new retrosynthetic strategy towards PAHs, especially polybenzoacenes.

Exploiting Cooperative Catalysis for the On‐Surface Synthesis of Linear Heteroaromatic Polymers via Selective C–H Activation

“…These synthetic protocols are particularly advantageous since biaryl linkages can be formed without any prefunctionalization of precursor molecules. Not surprisingly, the Scholl reaction proved to be most useful for the formation of multiple fused rings to obtain polycyclic arenes and nanographene compounds [5–9] . However, the C−H activation/arylation step in the synthesis of polycyclic aromatic hydrocarbons (PAHs) generally lacks selectivity because the C−H bonds have, besides a low intrinsic reactivity, only small relative differences in their reactivity [9, 10] .…”

Synthesis of Dibenzo[g,p]Chrysenes via Organophotocatalytic Sequential Single‐Electron Oxidation

“…The reaction of 3 in the presence of 4 equivalents of (PhS) 2 and a catalytic amount of Mes-Acr + ClO 4 À under 420 nm LED irradiation gave the corresponding tetracene 4 in 40% yield. In contrast with the conventional synthesis of these types of PAHs, which mainly involves transition metal catalysis or the Scholl reaction using FeCl 3 , [15,16] the present Mes-Acr + photocatalysis furnishes π-extended PAHs without requiring any metal reagent.…”

Einsatz der kooperativen Katalyse für die Oberflächensynthese linearer heteroaromatischer Polymere durch selektive C‐H‐Aktivierung

“…Diese Syntheseprotokolle sind besonders vorteilhaft, da Biarylbindungen ohne Vorfunktionalisierung der Vorläufermoleküle gebildet werden können. Es überrascht nicht, dass sich die Scholl‐Reaktion als besonders nützlich für die Bildung mehrerer kondensierter Ringe erwiesen hat, um polyzyklische Arene und Nanographenverbindungen zu erhalten [5–9] . Der Schritt der C‐H‐Aktivierung/Arylierung bei der Synthese polyzyklischer aromatischer Kohlenwasserstoffe (PAK) ist jedoch im Allgemeinen nicht sehr selektiv, da die C‐H‐Bindungen nicht nur eine geringe intrinsische Reaktivität aufweisen, sondern auch nur geringe relative Unterschiede in ihrer Reaktivität [9, 10] .…”