A Strategy for Selective Catalytic B–H Functionalization of o-Carboranes

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(21), P. 4065 - 4079

Published: Oct. 24, 2021

ConspectusCarboranes are a class of polyhedral carbon-boron molecular clusters featuring three-dimensional aromaticity, which often considered as 3D analogues benzene. Their unique structural and electronic properties make them invaluable building blocks for applications ranging from functional materials to versatile ligands pharmaceuticals. Thus, selective functionalization carboranes has received tremendous research interest. In earlier days, the vast majority works in this area were focused on cage carbon via facile deprotonation CH, followed by reaction with electrophiles. On contrary, B-H activation is very challenging since 10 bonds o-carborane similar, how achieve desired transformation at specific boron vertex long-standing issue.As more electronegative than boron, property results different charges cage, follow order B(3,6)-H ≪ B(4,5,7,11)-H < B(8,10)-H B(9,12)-H. We thought that difference may trigger favorite interaction proper transition metal complex bond carborane, could be utilized solve selectivity issue. Accordingly, our strategy described follows: (1) electron-rich catalysts good most electron-deficient (connected both C-H vertices); (2) relatively B(8,9,10,12)-H (with no bonding either (3) directing-group-assisted catalysis appropriate only one vertex), whose lie middle range bonds. This been successfully applied laboratory other groups development series synthetic routes catalytic carborane resulting synthesis large number cage-boron-functionalized derivatives regioselective fashion. Subsequently, significant progress emerging made.In 2013 we reported tetrafluorination o-carboranes using an Pd(II) salt, [Pd(MeCN)4][BF4], catalyst. 2014 disclosed first example carboxy-directed alkenylation B(4) promoted Ir(III) 2017 presented Ir(I)-catalyzed diborylation also uncovered Pd-catalyzed asymmetric chiral-at-cage 2018. These proof-of-principle studies have greatly stimulated activities enabled catalysts. so far developed toolbox methods B-olefination, -arylation, -alkenylation, -alkynylation, -oxygenation, -sulfenylation, -borylation, -halogenation, -amination. recently expanded base catalysis. As field progresses, expect will invented, detailed Account promote these efforts.

Language: Английский

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Chemistry of three-dimensional icosahedral boron clusters anions: closo-dodecaborate (2-) [B12H12]2- and carba-closo-dodecaborate(-) [CB11H12]-

Coordination Chemistry Reviews, Journal Year: 2024, Volume and Issue: 516, P. 215974 - 215974

Published: June 8, 2024

Language: Английский

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Functional Group Directed B–H Activation of Polyhedral Boron Hydrides by Transition Metal Complexes (Review)

Russian Journal of Inorganic Chemistry, Journal Year: 2021, Volume and Issue: 66(9), P. 1289 - 1342

Published: Sept. 1, 2021

Language: Английский

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Mechanochemical Solvent‐Free Suzuki–Miyaura Cross‐Coupling of Amides via Highly Chemoselective N−C Cleavage

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 61(7)

Published: Dec. 8, 2021

Although cross-coupling reactions of amides by selective N-C cleavage are one the most powerful and burgeoning areas in organic synthesis due to ubiquity amide bonds, development mechanochemical, solid-state methods remains a major challenge. Herein, we report first mechanochemical strategy for highly chemoselective, solvent-free palladium-catalyzed bond activation. The method is conducted absence external heating, short reaction time shows excellent chemoselectivity σ functional group tolerance can be applied late-stage functionalization complex APIs sequential orthogonal cross-couplings exploiting double solventless methods. results extend environments advance chemical repertoire interconversions environmentally friendly

Language: Английский

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Variable Metal Chelation Modes and Activation Sequence in Pd-Catalyzed B–H Poly-arylation of Carboranes

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(22), P. 14047 - 14057

Published: Nov. 4, 2021

The development of synthetic methods for selective multiple functionalization B–H bonds offers great opportunity in expanding the application potentials carboranes. Herein, regioselective poly-arylation o-, m-, and p-carboranes has been developed by imine-directed, Pd-catalyzed iterative activation. isolation key palladium intermediates early stage late palladation validates distinct chelation-assisted modes at PdII center during activation pathways. In particular, a scarce three-coordinated, T-shaped complex isolated proven to be effective subsequent arylation reaction. Stoichiometric control on catalytic penta-arylation p-carborane led exhaustive mono-, di-, tri-, tetra-, penta-arylated products, which provides rationale that 5-fold proceeds sequence from vertex B(2) B(4), then B(5), finally B(3) B(6). It is steric factor introduced aryl groups affects performance metal selectivity chelation mode. A series cage B(3,4,5,6)-tetra-arylated o-carboranes B(2,3,4,5,6)-penta-arylated m- were synthesized good excellent yields as an unreported type molecular propellers. utility this method also illustrated.

Language: Английский

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Practical Synthesis of B(9)-Halogenated Carboranes with N-Haloamides in Hexafluoroisopropanol

Inorganic Chemistry, Journal Year: 2022, Volume and Issue: 61(13), P. 5326 - 5334

Published: March 21, 2022

The B(9)-H halogenation of o-carborane and m-carborane was achieved with excellent selectivities in hexafluoroisopropanol (HFIP) under simple reaction conditions: single reagent [trichloroisocyanuric acid (TCCA), tribromoisocyanuric (TBCA) or N-iodosuccinimide (NIS)], catalyst-free, air-/moisture-tolerant, convenient work-up. With this method, a variety 9-halogenated o-carboranes m-carboranes were obtained good to yields broad tolerance functional groups.

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

Advanced Synthesis & Catalysis, Journal Year: 2022, Volume and Issue: 364(24), P. 4174 - 4188

Published: Dec. 1, 2022

Abstract 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 the B−H C−H functionalities carboranes been developed. These methods great success utilize directing groups, such carboxylic acids, to achieve selective functionalization carboranes. The carboxyl group can be easily introduced then removed after reactions. On other hand, assisted by highly regioselective electrophilic attack at electron‐rich positions B(4) B(5) cage generates five‐membered metallacyclic intermediates, which undergo further transformation. In this review, we show that transition metal‐catalyzed decarboxylation cross coupling reactions offer an opportunity for direct activation magnified image

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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Palladium-catalyzed selective B(3)–H arylation of o-carboranes with arylboronic acids at room temperature

Chemical Communications, Journal Year: 2021, Volume and Issue: 57(13), P. 1655 - 1658

Published: Jan. 1, 2021

A palladium-catalyzed selective B(3)–H arylation of o-carboranes under room temperature has been developed using readily available arylboronic acids as the aryl source, and corresponding 3-aryl-o-carboranes were obtained in good to excellent yields.

Language: Английский

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