Palladium-Catalyzed Regioselective B(3,4)–H Acyloxylation of <i>o</i>-Carboranes

Fu, Yatong; Yu, Li; Luo, Donghong; Lu, Yao; Huang, Jiajun; Yang, Ziyi; Lü, Jian; Jiang, Yuan‐Ye; Lu, Juyou

doi:10.1021/acs.inorgchem.1c02758

Cited by 15 publications

(2 citation statements)

References 59 publications

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“…We commenced our studies using readily available closo ‐carborane 1 [19a,20] and tris(4‐methoxyphenyl)phosphine as the model substrates in the presence of palladium catalyst (Table 1). Heating a mixture of 1 (1.0 equiv.)…”

Section: Resultsmentioning

confidence: 99%

Palladium‐Catalyzed Cascade Deboronation/Regioselective B−P Coupling of closo‐Carboranes

et al. 2022

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A cascade deboronation/regioselective BÀ P coupling of closocarboranes is disclosed using a combination of palladium catalysts and nitrogen or phosphine-containing directing groups. Unsymmetric C-substituted closo-carboranes, including C-monosubstituted and unsymmetric 1,2-disubstituted closocarboranes, are tolerated. Select closo-carboranes bearing other directing groups, such as benzoxazole, and diphenylphosphine, are compatible substrates for this reaction. Phosphine and arsenic can be utilized as effective coupling partners. Furthermore, a catalytic amount of palladium salt mediates the regioselective BÀ H activation process. Readily available closocarboranes as the starting materials for direct one-pot synthesis of functionalized nido-carboranes and the in-situ formation of nido-carborane intermediates without purification are important features in terms of practical applications.

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Section: Resultsmentioning

confidence: 99%

Palladium‐Catalyzed Cascade Deboronation/Regioselective B−P Coupling of closo‐Carboranes

et al. 2022

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“…Since the discovery of carboranes in the last century, their functionalization has been the central study in boron chemistry. In particular, the 3D cage structure of carboranes containing multiple B–H vertexes allows them to be substituted by various functional groups to construct B–C or B–X (X = heteroatoms) bonds. − In recent years, the fast development of B–H functionalization has offered an alternative and efficient pathway to synthesize the functionalized carborane derivatives. ,− However, it remains challenging to use these known synthetic schemes to readily access the aforementioned 2D–3D fused molecular systems as the following issues have to be addressed: (I) site-selective functionalization among the multiple B–H/C–H bonds; (II) realization of stepwise reactions in a one-pot manner; (III) the steric hindrance effect of 3D carborane; (IV) the side reactions associated with the B–H functionalization.…”

Section: Resultsmentioning

confidence: 99%

Facile Construction of New Hybrid Conjugation via Boron Cage Extension

et al. 2023

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Aromatic polycyclic systems have been extensively utilized as structural subunits for the preparation of various functional molecules. Currently, aromatics-based polycyclic systems are predominantly generated from the extension of two-dimensional (2D) aromatic rings. In contrast, polycyclic compounds based on the extension of three-dimensional (3D) aromatics such as boron clusters are less studied. Here, we report three types of boron cluster-cored tricyclic molecular systems, which are constructed from a 2D aromatic ring, a 3D aromatic nido-carborane, and an alkyne. These new tricyclic compounds can be facilely accessed by Pd-catalyzed B–H activation and the subsequent cascade heteroannulation of carborane and pyridine with an alkyne in an isolated yield of up to 85% under mild conditions without any additives. Computational results indicate that the newly generated ring from the fusion of the 3D carborane, the 2D pyridyl ring, and an alkyne is non-aromatic. However, such fusion not only leads to a 1H chemical shift considerably downfield shifted owing to the strong diatropic ring current of the embedded carborane but also devotes to new/improved physicochemical properties including increased thermal stability, the emergence of a new absorption band, and a largely red-shifted emission band and enhanced emission efficiency. Besides, a number of bright, color-tunable solid emitters spanning over all visible light are obtained with absolute luminescence efficiency of up to 61%, in contrast to aggregation-caused emission quenching of, e.g., Rhodamine B containing a 2D-aromatics-fused structure. This work demonstrates that the new hybrid conjugated tricyclic systems might be promising structural scaffolds for the construction of functional molecules.

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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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Palladium-Catalyzed Regioselective B(3,4)–H Acyloxylation of o-Carboranes

Cited by 15 publications

References 59 publications

Palladium‐Catalyzed Cascade Deboronation/Regioselective B−P Coupling of closo‐Carboranes

Palladium‐Catalyzed Cascade Deboronation/Regioselective B−P Coupling of closo‐Carboranes

Facile Construction of New Hybrid Conjugation via Boron Cage Extension

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

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