Synthesis of Carboranyl Alkyl Sulfide via Radical Thiol–Ene “Click” Reaction DOI
Dinghai Wang, Zhiyong He, Chang Liu

et al.

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: April 7, 2025

Synthetic methods that feature mild reaction conditions and broad functional group tolerance are highly desired for the development of third-generation boron delivery agents, which significant neutron capture therapy (BNCT), a selective cancer treatment technique. Molecules containing carborane promising candidates as compounds BNCT. Herein, we report an efficient radical thiol-ene "click" involving carboranyl thiols unactivated alkenes under photoredox conditions. This affords moderate to excellent isolated yields. The current methodology allows incorporation carborane, valuable moiety with high content, into molecules outstanding this method makes it suitable late-stage introduction bioactive molecules. addition reactivity thiol was investigated by DFT calculations uncover impact 3D aromaticity on stabilization sulfur centered radical.

Language: Английский

Organocatalytic Asymmetric Synthesis of o-Carboranyl Amines DOI
Hong‐Lei Xu,

Minghui Zhu,

Herman H. Y. Sung

et al.

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 14, 2025

Carboranyl amines are distinct from typical organic amines. Due to the electronic influence of carborane cage, they have low nucleophilicity and reluctant alkylate. Moreover, asymmetric synthesis chiral carboranes is still in its infancy. Herein we achieved first catalytic N-alkylation o-carboranyl amine, providing general access diverse secondary with high efficiency enantioselectivity under mild conditions. For time, organocatalysis was introduced chemistry. Key success use situ generated (naphtho-)quinone methides as alkylating reagents suitable acid catalysts. This protocol also applicable S-alkylation 1-SH-o-C2B10H11. Control experiments kinetic studies provided important insights into reaction mechanism, which likely involves rate-determining generation quinone methide followed by fast enantio-determining nucleophilic addition.

Language: Английский

Citations

2
Palladium-Catalyzed Regioselective B(9)-Amination of o-Carboranes and m-Carboranes in HFIP with Broad Nitrogen Sources DOI
Yan‐Na Ma, Hao Yan,

Yubin Ma

et al.

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(18), P. 8371 - 8378

Published: May 2, 2022

Amination of carboranes has a good application prospect in organic and pharmaceutical synthesis. However, the current methods used for this transformation suffer from limitations. Herein, we report practical method highly regioselective formation B-N bond by Pd(II)-catalyzed B(9)-H amination o- m-carboranes hexafluoroisopropanol (HFIP) with different nitrogen sources under air atmosphere. The silver salt HFIP solvent play critical roles present protocol. mechanistic study reveals that acts as Lewis acid to promote electrophilic palladation step forming heterobimetallic active catalyst PdAg(OAc)3; strong hydrogen-bond-donating ability low nucleophilicity enhance Pd(II). It is believed these N-containing are potentially great importance synthesis new pharmaceuticals.

Language: Английский

Citations

59
Facile Construction of New Hybrid Conjugation via Boron Cage Extension DOI

Fangxiang Sun,

Shuaimin Tan,

Hou‐Ji Cao

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(6), P. 3577 - 3587

Published: Feb. 6, 2023

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

Language: Английский

Citations

39
Direct B–H Functionalization of Icosahedral Carboranes via Hydrogen Atom Transfer DOI
Hongyuan Ren, Ping Zhang, Jingkai Xu

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7638 - 7647

Published: March 22, 2023

The efficient and selective functionalization of icosahedral carboranes (C2B10H12) at the boron vertexes is a long-standing challenge owing to presence 10 inert B-H bonds in similar chemical environment. Herein, we report new reaction paradigm for direct via homolysis enabled by nitrogen-centered radical-mediated hydrogen atom transfer (HAT) strategy. Both HAT process carborane bond resulting boron-centered carboranyl radical intermediate have been confirmed experimentally. occurs most electron-rich vertex with lowest dissociation energy (BDE). Using this strategy, diverse derivatization, including thiolation, selenation, alkynylation, alkenylation, cyanation, halogenation, achieved satisfactory yields under photoinitiated condition metal-free redox-neutral fashion. Moreover, synthetic utility current protocol was also demonstrated both scale-up construction carborane-based functional molecules. Therefore, methodology opens pathway functionalization, which distinct from heterolytic mechanism traditional strategies.

Language: Английский

Citations

30
B(9)-OH-o-Carboranes: Synthesis, Mechanism, and Property Exploration DOI
Yan‐Na Ma,

Huazhan Ren,

Yanxuan Wu

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7331 - 7342

Published: March 24, 2023

Herein, we present a chemically robust and efficient synthesis route for B(9)-OH-o-carboranes by the oxidation of o-carboranes with commercially available 68% HNO3 under assistance trifluoromethanesulfonic acid (HOTf) hexafluoroisopropanol (HFIP). The reaction is highly wide scope carboranes, selectivity B(9)/B(8) up to 98:2. success this transformation relies on strong electrophilicity oxidizability HNO3, promoted through hydrogen bonds Brønsted HOTf solvent HFIP. Mechanism studies reveal that o-carborane involves an initial electrophilic attack atom at most electronegative B(9) o-carborane. In transformation, B-H bond nucleophilic site, which different from substitution reaction, where boron site. Therefore, oxidation-reduction mild conditions in N(V) → N(III) H(-I) H(I). derivatization 9-OH-o-carborane was further examined, carboranyl group successfully introduced amino acid, polyethylene glycol, biotin, deoxyuridine, saccharide. Undoubtedly, approach provides selective way rapid incorporation carborane moieties into small molecules application neutron capture therapy, requires targeted delivery boron-rich groups.

Language: Английский

Citations

24
Photoinduced Selective B–H Activation of nido-Carboranes DOI

Sheng‐Wen Xu,

Hongjian Zhang, Jingkai Xu

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(11), P. 7791 - 7802

Published: March 10, 2024

The development of new synthetic methods for B–H bond activation has been an important research area in boron cluster chemistry, which may provide opportunities to broaden the application scope clusters. Herein, we present a reaction strategy direct site-selective functionalization nido-carboranes initiated by photoinduced cage via noncovalent cage···π interaction. As result, nido-carborane radical is generated through single electron transfer from 3D 2D photocatalyst upon irradiation with green light. resulting transient could be directly probed advanced time-resolved EPR technique. In air, subsequent transformations active have led efficient and selective B–N, B–S, B–Se couplings presence N-heterocycles, imines, thioethers, thioamides, selenium ethers. This protocol also facilitates both late-stage modification drugs synthesis nido-carborane-based drug candidates neutron capture therapy (BNCT).

Language: Английский

Citations

13
Theoretical study on precise regulation of ESIPT reaction based on ICT effect of o-carborane derivatives DOI

Zuzhi Chen,

Xiaoyang Liu, Dan Zhang

et al.

Journal of Molecular Structure, Journal Year: 2024, Volume and Issue: 1321, P. 139985 - 139985

Published: Sept. 10, 2024

Language: Английский

Citations

9
Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane DOI Creative Commons
Zahra Noori, Miquel Solà, Clara Viñas

et al.

Beilstein Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: 21, P. 412 - 420

Published: Feb. 21, 2025

A new series of o -carborane-fused pyrazoles has been recently successfully synthesized. This fusion was expected to create a hybrid 3D/2D aromatic system, combining the 3D aromaticity -carborane with 2D pyrazole. However, while boron cage retains its character, pyrazole’s is lost. As result, rather than forming pyrazoles, synthesis yielded pyrazolines, which are non-aromatic. The limited overlap between π molecular orbitals (MOs) planar heterocycle and n + 1 MOs carborane prevents significant electronic delocalization two fused components. contrasts pyrazole benzene form indazole, where both rings maintain their aromaticity. Our findings demonstrate that peripheral σ-aromaticity π-aromaticity orthogonal, making true system unachievable. highly aromatic, generating negative NICS values (−25 −30 ppm). We have observed these high extend rings, leading incorrect estimations Therefore, relying solely on can be misleading, other computational indicators, along experimental or structural data, should used accurately assess

Language: Английский

Citations

1
Visible-Light-Promoted Nickel-Catalyzed Cross-Coupling of Iodocarboranes with (Hetero)Arenes via Boron-Centered Carboranyl Radicals DOI
Shimeng Li, Zuowei Xie

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(18), P. 7960 - 7965

Published: April 22, 2022

A general strategy for the generation of hypervalent boron-centered carboranyl radicals at B(3), B(4), and B(9) positions has been developed first time via visible-light-promoted iodine atom abstraction from iodo-o-carboranes by low-valent nickel complex. These react with various (hetero)arenes to afford a wide range cage B-arylated carborane derivatives room temperature in very good excellent yields broad substrate scope. Their electrophilicities are dependent on vertex charges follow order B(3) > B(4) B(9). Both visible light catalyst proved critical radicals. The involvement boron is supported control experiments. reaction mechanism associated these reactions also proposed. This offers new protocol selected vertex, leading facile synthesis large class substituted molecules.

Language: Английский

Citations

34
Electrochemical Cage Activation of Carboranes DOI Creative Commons
Long Yang, Zijing Zhang,

Becky Bongsuiru Jei

et al.

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(20)

Published: Feb. 11, 2022

Abstract Carboranes are boron–carbon molecular clusters that possess unique properties, such as their icosahedron geometry, high boron content, and delocalized three‐dimensional aromaticity. These features render carboranes valuable building blocks for applications in supramolecular design, nanomaterials, optoelectronics, organometallic coordination chemistry, neutron capture therapy (BNCT) agents. Despite tremendous progress this field, stoichiometric chemical redox reagents largely required the oxidative activation of carborane cages. In context, electrosyntheses represent an alternative strategy more sustainable syntheses. It is only recent few years considerable has been made electrochemical cage functionalization carboranes, which summarized Minireview. We anticipate electrocatalysis will serve increasingly powerful stimulus within current renaissance electrochemistry.

Language: Английский

Citations

33