Palladium-Catalyzed Regioselective B(9)-Amination of o-Carboranes and m-Carboranes in HFIP with Broad Nitrogen Sources

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

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B(9)-OH-o-Carboranes: Synthesis, Mechanism, and Property Exploration

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

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Photoinduced Selective B–H Activation of nido-Carboranes

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

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Iridium-Catalyzed Selective B(4)–H Acylmethylation of o-Carboranes with Sulfoxonium Ylides

Organic Letters, Journal Year: 2022, Volume and Issue: 24(6), P. 1318 - 1322

Published: Feb. 7, 2022

A highly efficient Ir-catalyzed regioselective cage B(4)-H acylmethylation of o-carboranyl acids using sulfoxonium ylides as alkylating regents has been developed, leading to the preparation a large class B(4)-acylmethylated o-carboranes in good excellent yields with broad substrate scope under redox neutral conditions. The -COOH moiety serves traceless directing group and controls regioselectivity monoselectivity.

Language: Английский

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Iridium(III)-Catalyzed B(4)-Acylmethylation and B(3,5)-Diacylmethylation from o-Carboranes and Sulfoxonium Ylides

Organic Letters, Journal Year: 2022, Volume and Issue: 24(8), P. 1604 - 1609

Published: Feb. 17, 2022

An iridium(III)-catalyzed regioselective acylmethylation of the cage B(4)-H bond in o-carborane acids with sulfoxonium ylides is demonstrated through activation ethanol under very mild conditions, affording a number B(4)-acylmethylated o-carboranes. Additionally, selective sequential B(4)- and B(6)-acylmethylation reactions finally gave B(3,5)-diacylmethylated o-carboranes one pot.

Language: Английский

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A strategy for regioselective B–H functionalization ofo-carboranesviabase metal catalysis

Organic Chemistry Frontiers, Journal Year: 2023, Volume and Issue: 10(12), P. 3074 - 3079

Published: Jan. 1, 2023

This frontier article summarizes the recent developments in base metal-catalyzed regioselective cage B–H functionalization of carboranes and discusses related challenging issues.

Language: Английский

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Application of the aza-Wittig reaction for the synthesis of carboranyl Schiff bases, benzothiazoles and benzoselenazolines

Dalton Transactions, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

The aza-Wittig reaction was successfully applied to the synthesis of carboranyl-imines, which are difficult obtain by classical methods. A variety functionalized carboranyl Schiff bases obtained proving great scope methodology. All compounds were fully characterized, including solid-state structures six them. modified permit in one step carboranyl-benzothiazole and carboranyl-benzoselenazoline derivatives. stability studies show that carboranyl-imines benzothiazole promote deboronation nido-derivatives, is achieved simple with methanol or protic solvents. nido-derivatives also studied X-ray diffraction. In contrast, saturated derivatives, amine benzoselenazoline, do not stable

Language: Английский

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Chelating 1,2-Bis(2′-picolyl)-o-carborane as a Supporting Ligand for Pd-Catalyzed Selective B(3,6)–H Difunctionalization of o-Carboranes

Inorganic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 11, 2025

Transition metal catalyzed selective cage B–H functionalization of carboranes has made significant progress in recent years, giving rise to the efficient synthesis a large variety B-functionalized including alkenylation, arylation, alkynylation, borylation, hydroxylation, acyloxylation, amination, and halogenation. However, mechanisms these catalytic B–X coupling reactions are not well understood. Herein, we describe isolation characterization catalytically relevant o-carborane based palladium(II) metallacycle, disclosing details Pd-catalyzed o-carboranes. As result, highly B(3,6)-dihalogenation, -dimethylation, -diarylation o-carboranes have been achieved.

Language: Английский

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Taming Inert B–H Bond with Low Energy Light: A Near-Infrared Light-Induced Approach to Facile Carborane Cluster-Amino Acid Coupling

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

Published: April 1, 2025

The selective functionalization of inert B–H bonds in carborane clusters has been a formidable challenge. Recent advances have witnessed such reactions through photoredox methods utilizing ultraviolet or visible light irradiation. However, high-energy sources often suffer from poor energy efficiency, limited substrate scope, undesired side reactions, and low scalability. Here, we present the first successful bond under low-energy near-infrared (NIR) using carborane-based electron donor–acceptor complex. Both photophysical investigations theoretical modeling reveal facile single-electron transfer cage to electron-deficient photocatalyst, generating radical NIR follow-up pathway enables direct coupling carboranes with amino acids oligopeptides, yielding diverse array carborane-functionalized oligopeptides. Beyond expanding known chemical space boron cluster derivatives, further demonstrate that imaging targeting capabilities could serve as promising multifunctional carriers for neutron capture therapy. Thus, via not only provides straightforward practical strategy synthetic chemistry but also lays foundation development next-generation boron-containing biomolecules advanced functional materials.

Language: Английский

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Polyoxometalate-Supported Pd(II)-Catalyzed B(9)–H Nitration of o/m-Carboranes

ACS Catalysis, Journal Year: 2025, Volume and Issue: unknown, P. 7646 - 7652

Published: April 23, 2025

Language: Английский

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