Synthesis of Carbazole-Fused Azaborines via a Pd-Catalyzed C-H Activation-Cyclization Reaction

Nagata, Masakazu; Oshiro, Taku; Mizuhata, Yoshiyuki; Tokitoh, Norihiro; Hosoya, Takamitsu; Yamada, Shigeyuki; Konno, Tsutomu; Fukumoto, Hiroki; Kubota, Toshio; Agou, Tomohiro

doi:10.1246/bcsj.20200129

Cited by 6 publications

(7 citation statements)

References 36 publications

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“…Through fusing carbazole moieties, compounds 45 showed improved PLQY and higher electrochemical stability. [ 23 ] On the other hand, Kawashima and co‐workers further studied the functionalization of 1,4‐azaborine‐embedded anthracenes at the nitrogen position and synthesized donor–acceptor type π ‐conjugated dendrimers 46 successfully. [ 12c ] The emission of dendrimers 46a and 46c both revealed obviously bathochromic shift ( λ em > 600 nm) because of the intramolecular charge transfer (ICT) from the azaborine dendrons to the benzothiadiazole core.…”

Section: Synthetic Strategiesmentioning

confidence: 99%

The Rise of 1,4‐BN‐Heteroarenes: Synthesis, Properties, and Applications

Chen

2022

Advanced Science

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Dedicated to Professor Klaus Müllen on the occasion of his 75th birthdayBN-heteroarenes, which employ both boron and nitrogen in aromatic hydrocarbons, have gained great attention in the fields of organic chemistry and materials science. Nevertheless, the extensive studies on BN-heteroarenes are largely limited to 1,2-azaborine-based compounds with B-N covalent bonds, whereas 1,3-and 1,4-BN-heteroarenes are relatively rare due to their greater challenge in the synthesis. Recently, significant progresses have been achieved in the synthesis and applications of BN-heteroarenes featuring 1,4-azaborines, especially driven by their significant potential as multiresonant thermally activated delayed fluorescence (MR-TADF) materials. Therefore, it is timely to review these advances from the chemistry perspective. This review summarizes the synthetic methods and recent achievements of 1,4-azaborine-based BN-heteroarenes and discusses their unique properties and potential applications of this emerging class of materials, highlighting the value of 1,4-BN-heteroarenes beyond MR-TADF materials. It is hoped that this review would stimulate the conversation and cooperation between chemists who are interested in azaborine chemistry and materials scientists working in the fields of organic optoelectronics, metal catalysis, and carbon-based nanoscience etc.

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Section: Synthetic Strategiesmentioning

confidence: 99%

The Rise of 1,4‐BN‐Heteroarenes: Synthesis, Properties, and Applications

Chen

2022

Advanced Science

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“…Carbazole-fused 1,4-azaborines were successfully synthesized via palladium-catalyzed C–H activation. 33 Precursors 62 of the C–H activation were prepared by the Buchwald–Hartwig amination reaction starting from dibromodibenzo-fused 1,4-azaborine 50 and o -chloroanilines. Palladium-catalyzed C–H activation at the para -positions to the boron atom provided the desired carbazole-fused 1,4-azaborines 63 .…”

Section: Dibenzo-fused 14-azaborines and Their Derivativesmentioning

confidence: 99%

1,4-Azaborines: Origin, Modern Synthesis, and Applications as Optoelectronic Materials

2021

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This short review summarizes the origins and recent progress in 1,4-azaborine research, focusing on synthetic methodologies. Academic laboratories have made significant efforts to generate boron-nitrogen-containing heteroaromatic compounds that mimic arenes. 1,2-, 1,3-, and 1,4-Azaborine motifs have provided breakthrough molecules in applications ranging from medicines to materials. Owing to recent advances in polyaromatic 1,4-azaborine synthesis and applications in industry, the research field is currently undergoing a renaissance. Photo- and electroluminescent properties driven by distinct structural variations are key components in the design of novel 1,4-azaborine structures. In this review, seminal reports on the synthesis of simple 1,4-azaborines to complex π-extended structures are briefly highlighted together along with key optoelectronic properties.1 Introduction2 Non-Fused 1,4-Azaborines3 Monobenzo-Fused 1,4-Azaborines4 Dibenzo-Fused 1,4-Azaborines and Their Derivatives5 Ladder-Type 1,4-Azaborines6 Complex 1,4-Azaborines7 Optoelectronic Properties of Key 1,4-Azaborines8 Conclusion and Outlook

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“…In contrast, the previously reported route to carbazole-fused 1,4-azaborines required the initial synthesis of a dibrominated dibenzo-fused 1,4-azaborine (related to 4e), which was used in a HB-coupling reaction with ortho-chloro-aniline, followed by a palladium catalyzed C−C bond forming reaction to make the carbazole fused 1,4azaborine. 34 Next, the construction of multiple 1,4-azaborine units in one PAH via this methodology was explored. However, multiple attempts to form the B 2 N 2 pentacene 4o via this methodology proved unsuccessful (with <5% of the desired product isolated), this included using more forcing conditions.…”

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confidence: 99%

“…Presumably, the N-Ph unit provides sufficient steric shielding of its ortho C–H position to prevent any observable borylation at that site. Carbazole-fused 1,4-azaborines are of interest as compounds related to 4n have been reported previously to have superior photophysical properties and electrochemical stability relative to dibenzofused-1,4-azaborines . The extended heterocyclic cores of 4m and 4n are novel structures to the best of our knowledge; furthermore, they are accessible in one pot from 1m/1n , with 1m and 1n themselves accessible in two simple steps from commercial precursors (a HB coupling and then an acylation).…”

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confidence: 99%

Borylation–Reduction–Borylation for the Formation of 1,4-Azaborines

Kothavale,

Iqbal,

Hanover

et al. 2023

Org. Lett.

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Given the current interest in materials containing 1,4-azaborine units, the development of new routes to these structures is important. Carbonyl directed electrophilic borylation using BBr 3 is a facile method for the ortho -borylation of N , N -diaryl-amide derivatives. Subsequent addition of Et 3 SiH results in carbonyl reduction and then formation of 1,4-azaborines that can be protected in situ using a Grignard reagent. Overall, borylation–reduction–borylation is a one-pot methodology to access 1,4-azaborines from simple precursors.

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Synthesis of Carbazole-Fused Azaborines via a Pd-Catalyzed C-H Activation-Cyclization Reaction

Cited by 6 publications

References 36 publications

The Rise of 1,4‐BN‐Heteroarenes: Synthesis, Properties, and Applications

The Rise of 1,4‐BN‐Heteroarenes: Synthesis, Properties, and Applications

1,4-Azaborines: Origin, Modern Synthesis, and Applications as Optoelectronic Materials

Borylation–Reduction–Borylation for the Formation of 1,4-Azaborines

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