Fusing Carborane Carboxylic Acids with Alkynes: 3D Analogues of Isocoumarins via Regioselective B−H Activation

Lin, Furong; Shen, Yunjun; Zhang, Yuanbin; Sun, Yujia; Liu, Jiyong; Duttwyler, Simon

doi:10.1002/chem.201703802

Cited by 46 publications

(7 citation statements)

References 162 publications

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“…Strong electrophiles E + preferentially attack B–H vertices most distant from the cage carbon atoms in the icosahedral framework, leading to the formation of new B–E bond(s) and release of H + (Scheme a). , Such reactions proceed stepwise in the order B(9,12)–H > B(8,10)–H > B(4,5,7,11)–H ≫ B(3,6)–H, which corresponds to the charge distribution of the cage (see Scheme for the numbering system) . It is noted that the degree of substitution in the aforementioned electrophilic reactions has hardly been controlled by electronic effects. , However, in the case of transition metal electrophiles, selective cage B–H metalation has been achieved via tuning of the bulkiness of the coordinating ligands and/or the directing-group strategy, which has led to the development of catalytic selective functionalization of cage B–H vertices. , …”

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confidence: 99%

Regioselective Nucleophilic Alkylation/Arylation of B–H Bonds in o-Carboranes: An Alternative Method for Selective Cage Boron Functionalization

Tang

Zhang

et al. 2018

J. Am. Chem. Soc.

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A new protocol for regioselective nucleophilic cage B−H substitution in o-carboranes has been proposed that is complementary to the strategies of transition metal catalysis and electrophilic substitution. Magnesium-mediated site-selective nucleophilic cage B-(3,6)−H and B(9)−H substitution reactions of ocarboranes give a series of B(3,6)-dialkylated and B(9)alkylated/arylated o-carboranes in high yields. Both steric and electronic factors of cage C substituents play crucial roles in controlling the site selectivity.

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confidence: 99%

Regioselective Nucleophilic Alkylation/Arylation of B–H Bonds in o-Carboranes: An Alternative Method for Selective Cage Boron Functionalization

Tang

Zhang

et al. 2018

J. Am. Chem. Soc.

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“…Thus, an iridium‐catalyzed annulation reaction between monocarba‐ closo ‐dodecaborate carboxylic acids and diarylacetylene was reported by Duttwyler's group in 2017 (Scheme 11). [23] Series of 3D bora‐analogues of isocoumarins were synthesized via regioselective B(2)−H Activation. In addition, the second substitution occurred at the B4 position to afford B2/4‐disubstituted products.…”

Section: Formation Of B−c(sp2) Bondsmentioning

confidence: 99%

Recent Advance in Transition Metal‐Catalyzed Carboxylic Acid Guided B−H Functionalization of Carboranes

et al. 2022

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Carboranes, a three-dimensional class of carbon-boron molecular clusters with remarkable electronic, physical, chemical characteristics, have proved as useful building blocks in boron neutron capture therapy agents, supramolecular design, optoelectronics, nanomaterials and organometallic/coordination chemistry. Thus, various organic modifications of the BÀ H and CÀ H functionalities in carboranes have been developed. These methods with great success utilize directing groups, such as carboxylic acids, to achieve a selective BÀ H functionalization of carboranes. The carboxyl group can be easily introduced to carboranes and then be removed after reactions. On the other hand, assisted by the carboxyl group a highly regioselective electrophilic attack at the electron-rich positions B(4) and B(5) of the cage generates five-membered metallacyclic intermediates, which then undergo further transformation. In this review, we show that transition metal-catalyzed decarboxylation cross coupling reactions offer an opportunity for the selective and direct BÀ H activation of carboranes. 1. Introduction 2. Formation of BÀ C(sp 2 ) Bonds 3. Formation of BÀ C(sp) Bonds 4. Formation of BÀ C(sp 3 ) Bonds 5. Formation of BÀ N Bonds 6. Formation of BÀ O Bonds 7. Formation of BÀ X Bonds 8. Formation of BÀ N Bonds and BÀ C(sp 2 ) Bonds 9. Formation of CÀ N Bonds 10. Conclusions and Outlooks

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“…According to the carboxylic acid directed selective B-H activation of o-carboranes [30][31][32][33][34][35][36][37], by introducing carboxylic acid into cage carbon of monocarba-closo-dodecaborate (CB 11 − ), the iridium-catalyzed B-H activation/alkenylation/annulation of CB 11 − cluster with diarylacetylenes for synthesis of 3D analogues of isocoumarins was accomplished in Duttwyler's group [50]. This transformation displays broad substrate scope for kinds of symmetric diarylacetylenes as well as unsymmetric internal alkynes (Figure 4).…”

Section: Synthesis Of [Cb 11 ] − -Fused Heterocyclementioning

confidence: 99%

Synthesis of Polyhedral Borane Cluster Fused Heterocycles via Transition Metal Catalyzed B-H Activation

Cao

Zhang

et al. 2020

Molecules

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Aromatic heterocycles are ubiquitous building blocks in bioactive natural products, pharmaceutical and agrochemical industries. Accordingly, the carborane-fused heterocycles would be potential candidates in drug discovery, nanomaterials, metallacarboranes, as well as photoluminescent materials. In recent years, the transition metal catalyzed B-H activation has been proved to be an effective protocol for selective functionalization of B-H bond of o-carboranes, which has been further extended for the synthesis of polyhedral borane cluster-fused heterocycles via cascade B-H functionalization/annulation process. This article summarizes the recent progress in construction of polyhedral borane cluster-fused heterocycles via B-H activation.

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Fusing Carborane Carboxylic Acids with Alkynes: 3D Analogues of Isocoumarins via Regioselective B−H Activation

Cited by 46 publications

References 162 publications

Regioselective Nucleophilic Alkylation/Arylation of B–H Bonds in o-Carboranes: An Alternative Method for Selective Cage Boron Functionalization

Regioselective Nucleophilic Alkylation/Arylation of B–H Bonds in o-Carboranes: An Alternative Method for Selective Cage Boron Functionalization

Recent Advance in Transition Metal‐Catalyzed Carboxylic Acid Guided B−H Functionalization of Carboranes

Synthesis of Polyhedral Borane Cluster Fused Heterocycles via Transition Metal Catalyzed B-H Activation

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