Catalytic Double Carbon-Boron Bond Formation for the Synthesis of Cyclic Diarylborinic Acids as Versatile Building Blocks for π-Extended Heteroarenes

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

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 BBr3 is a facile method for the ortho-borylation of N,N-diaryl-amide derivatives. Subsequent addition of Et3SiH 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.

Recent Expedition in Pd- and Rh-Catalyzed C(Ar) -B Bond Formations and Their Applications in Modern Organic Syntheses

Transition metal-catalyzed borylation has emerged as a powerful and versatile strategy for synthesizing organoboron compounds. These compounds have found widespread applications in various aspects, including organic synthesis, materials science, and medicinal chemistry. This review provides a concise summary of the recent advances in palladium- and rhodium-catalyzed borylation from 2013 to 2023. The review covers the representative examples of catalysts, substrates scope and reaction conditions, with particular emphasis on the development of catalyst systems, such as phosphine ligands, NHC-carbene, and more. The diverse array of borylative products obtained for further applications in Suzuki-Miyaura coupling, and other transformations, are also discussed. Future directions in this rapidly evolving field, with the goal of designing more efficient, selective borylation methodologies are highlighted, too.

Recent Advances in the Synthesis of Borinic Acid Derivatives

Borinic acids [R2B(OH)] and their chelate derivatives are a subclass of organoborane compounds used in cross-coupling reactions, catalysis, medicinal chemistry, polymer or optoelectronics materials. In this paper, we review the recent advances in the synthesis of diarylborinic acids and their four-coordinated analogs. The main strategies to build up borinic acids rely either on the addition of organometallic reagents to boranes (B(OR)3, BX3, aminoborane, arylboronic esters) or the reaction of triarylboranes with a ligand (diol, amino alcohol, etc.). After general practical considerations of borinic acids, an overview of the main synthetic methods, their scope and limitations is provided. We also discuss some mechanistic aspects.

Transition-Metal-Free Heterocyclic Carbon-Boron Bond Formation

Heteroaryl boronic acids and esters are extremely important and valuable intermediates because of their wide application in the synthesis of marketed drugs and bioactive compounds. Over the last couple of decades, the construction of highly important heteroaryl carbon-boron bonds has created huge attention. The transition-metal-free protocols are more green, less sensitive to air and moisture, and also economically advantageous over the transition-metal-based protocols. The transition-metal-free C-H borylation of heteroarenes and C-X (X=halogen) borylation of heteroaryl halides represents an excellent approach for their synthesis. Also, various cyclization and alkyne activation protocols have been recently established for their synthesis. The goal of this review article is to summarize the existing literature and the current state of the art for transition-metal-free synthesis of heteroaryl boronic acid and esters.

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

BN-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.

Aminoboranes via Tandem Iodination/Dehydroiodination for One-Pot Borylation

A rapid synthesis of aminoboranes from amine-boranes utilizing an iodination/dehydroiodination sequence is described. Monomeric aminoboranes are generated exclusively from several substrate adducts, following an E2-type elimination, with the added base playing a critical role in monomer vs dimer formation. Diisopropylaminoborane formed using this methodology has been applied to a one-pot palladium-catalyzed conversion of iodo- and bromoarenes to the corresponding boronates. Additionally, modification of the workup allows for isolation of the boronic acid and recovery of the utilized amine.

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

This review surveys recent progress in the chemistry of polycyclic heteroaromatic molecules with a focus on structural diversity and synthetic methodology. The article covers literature published during the period of 2016-2020, providing an update to our first review of this topic (Chem. Rev. 2017, 117 (4), 3479-3716).

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

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 Introduction

2 Non-Fused 1,4-Azaborines

3 Monobenzo-Fused 1,4-Azaborines

4 Dibenzo-Fused 1,4-Azaborines and Their Derivatives

5 Ladder-Type 1,4-Azaborines

6 Complex 1,4-Azaborines

7 Optoelectronic Properties of Key 1,4-Azaborines

8 Conclusion and Outlook

Catalyst-Free Synthesis of O-Heteroacenes by Ladderization of Fluorinated Oligophenylenes

A novel catalyst-free approach to benzoannulated oxygen-containing heterocycles from fluorinated oligophenylenes is reported. Unlike existing methods, the presented reaction does not require an oxygen-containing precursor and relies on an external oxygen source, potassium tert-butoxide, which serves as an O2- synthon. The radical nature of the reaction facilitates nucleophilic substitution even in the presence of strong electron-donating groups and enables de-tert-butylation required for the complete annulation. Also demonstrated is the applicability of the method to introduce five-, six-, and seven-membered rings containing oxygen, whereas multiple annulations also open up a short synthetic path to ladder-type O-heteroacenes and oligodibenzofurans.

Application of Palladium-Catalyzed Cross-Coupling Reactions in Organic Synthesis

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Palladium-catalyzed cross-coupling reactions have gained a continuously growing interest of synthetic organic chemists. The present review gives a brief account of applications of the palladium-catalyzed cross-coupling reactions in comprehensive synthesis, viz., the Heck, Stille, Suzuki–Miyaura, Negishi, Sonogashira, Buchwald–Hartwig, Ullmann and the Oxidative, decarboxylative cross-coupling reactions, with particular emphasis on the synthesis of heterocyclic compounds.

Chlorine-Substituted 9,10-Dihydro-9-aza-10-boraanthracene as a Precursor for Various Boron- and Nitrogen-Containing π-Conjugated Compounds

Chlorine-substituted 9,10-dihydro-9-aza-10-boraanthracene was synthesized. Derivatization of this compound by taking advantage of the transformable B-Cl moiety gave 9,10-dihydro-9-aza-10-boraanthracene derivatives with various aryl substituents. In addition, further functionalization on NH groups by alkylation and Buchwald-Hartwig amination was demonstrated. Photophysical properties of the resulting 9,10-dihydro-9-aza-10-boraanthracene derivatives were also discussed.

Featuring Xantphos

This review highlights the use of the bisphosphine ligand group in homogeneous catalysis.