Controlled functionalization ofo-carboraneviatransition metal catalyzed B–H activation

Chemical Society Reviews, Journal Year: 2019, Volume and Issue: 48(13), P. 3660 - 3673

Published: Jan. 1, 2019

This review summarizes recent advances in transition metal catalyzed vertex-specific BH functionalization ofo-carborane for controlled synthesis of its derivatives.

Language: Английский

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Aggregation‐Induced Electrochemiluminescence of Carboranyl Carbazoles in Aqueous Media

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(10), P. 3162 - 3166

Published: Jan. 30, 2019

Abstract The aggregation‐induced electrochemiluminescence (AIECL) of carboranyl carbazoles in aqueous media was investigated for the first time. Quantum yields, morphologies, and particle sizes were observed to determine (ECL) performance these aggregated organic dots (ODs). All compounds exhibit much higher ECL stability intensity than carborane‐free compound, demonstrating essential role motif. Moreover, results cyclic voltammetry (CV) suggest that oxidation/reduction reactions take place at excited states ODs proposed be generated by mechanism surface state transitions. More importantly, show a reductive–oxidative contrast other materials oxidative–reductive mechanisms. Our experiments data have established relation between AIE structures properties has strong potential biological diagnostic applications.

Language: Английский

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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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Transient imines as ‘next generation’ directing groups for the catalytic functionalisation of C–H bonds in a single operation

Organic & Biomolecular Chemistry, Journal Year: 2018, Volume and Issue: 16(25), P. 4582 - 4595

Published: Jan. 1, 2018

C-H functionalisation promises a paradigm shift in synthetic planning. However, the additional steps often required to install and remove directing groups currently detract from efficiency. The strategy of reversible installation group via an imine linkage has recently emerged, with formed hydrolysed situ. Such transient can promote transition metal catalysed unactivated bonds aldehydes, ketones amines. This approach removes usually for covalent use catalytic quantities forming component. review updates rapidly developing field on sp2 sp3 carbon centres, form new C-C C-X bonds. We focus structures as mono or bidentate coordinating various catalysts.

Language: Английский

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Palladium-Catalyzed Selective Five-Fold Cascade Arylation of the 12-Vertex Monocarborane Anion by B–H Activation

Journal of the American Chemical Society, Journal Year: 2018, Volume and Issue: 140(42), P. 13798 - 13807

Published: Sept. 19, 2018

A series of cage penta-arylated carboranes have been synthesized by palladium-catalyzed intermolecular coupling the C-carboxylic acid monocarba- closo-dodecaborate anion [CB11H12]- with iodoarenes direct B-H bond functionalization. These transformations set a record in terms one-pot directing group-mediated activation inert bonds single molecule. The methodology is characterized high yields, good functional group tolerance, and complete regioselectivity. COOH can be easily removed during or after reaction. mechanistic pathways were probed using density theory calculations. Pd(II)-Pd(IV)-Pd(II) catalytic cycle proposed, which initial followed preferred adjacent boron vertex, continuation this selectivity results continuous walking process palladium center. opens new avenue toward building blocks 5-fold symmetry.

Language: Английский

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Recent Advances in Transition Metal-Catalyzed Selective B-H Functionalization ofo-Carboranes

Bulletin of the Chemical Society of Japan, Journal Year: 2020, Volume and Issue: 94(3), P. 879 - 899

Published: Dec. 18, 2020

Abstract Carboranes are a class of carbon-boron molecular clusters, possessing extraordinary characteristics including three-dimensional aromaticity conjugated by σ-bonds, icosahedral geometry and inherent robustness. They finding growing applications as valuable building blocks in boron neutron capture therapy agents, pharmacophores, nanomaterials, optoelectronic, organometallic/coordination chemistry more. Therefore, the effective controlled functionalization carboranes has attracted enormous research interests, particularly regio- enantio-selective cage BH derivatization among ten chemically similar vertices o-carboranes. Only recent few years, significant progress been made transition metal catalyzed vertex-specific functionalization. This review summarizes advances this realm.

Language: Английский

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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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Catalytic Cascade Dehydrogenative Cross-Coupling of BH/CH and BH/NH: One-Pot Process to Carborano-Isoquinolinone

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(32), P. 12855 - 12862

Published: July 15, 2019

A proof-of-principle study of cascade dehydrogenative cross-coupling carboranyl carboxylic acid with readily available benzamide has been achieved, resulting in the facile synthesis previously inaccessible carborano-isoquinolinone derivatives a simple one-pot process, which two cage B-H, one aryl C-H, and N-H bond were sequentially activated to construct efficiently new B-C B-N bonds, respectively. Under suitable reaction conditions, such cyclization can be stopped at first B-H/C-H step give series α-carboranyl benzamides, suggesting preferential occurrence over that B-N. The directing group plays key role step, is then removed through situ decarboxylation. CV results combined control experiments indicate high-valent Ir(V)-species may involved pathways, crucial for reactions. isolation structural identification intermediate, its controlled transformations, deuterium labeling support Ir-nitrene-mediated amination B-H/N-H dehydrocoupling.

Language: Английский

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Catalytic Regioselective Cage B(8)–H Arylation of o-Carboranes via “Cage-Walking” Strategy

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(10), P. 4219 - 4224

Published: Feb. 24, 2019

A proof-of-concept example of catalytic regioselective cage B(8)-H functionalization o-carboranes has been disclosed for the first time. Under help an acylamino directing group at B(3), a series B(8)-arylated, B(4,7,8)-triarylated and B(4,7,8)-trifluorinated o-carborane derivatives were conveniently prepared. On basis isolation key intermediate, deuterium labeling experiments DFT calculations, reaction mechanism involving high-valent palladium induced "cage-walking" from B(4) to B(8) vertex is proposed account activation.

Language: Английский

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Aggregation‐Induced Electrochemiluminescence of Carboranyl Carbazoles in Aqueous Media

Angewandte Chemie, Journal Year: 2019, Volume and Issue: 131(10), P. 3194 - 3198

Published: Jan. 30, 2019

Abstract The aggregation‐induced electrochemiluminescence (AIECL) of carboranyl carbazoles in aqueous media was investigated for the first time. Quantum yields, morphologies, and particle sizes were observed to determine (ECL) performance these aggregated organic dots (ODs). All compounds exhibit much higher ECL stability intensity than carborane‐free compound, demonstrating essential role motif. Moreover, results cyclic voltammetry (CV) suggest that oxidation/reduction reactions take place at excited states ODs proposed be generated by mechanism surface state transitions. More importantly, show a reductive–oxidative contrast other materials oxidative–reductive mechanisms. Our experiments data have established relation between AIE structures properties has strong potential biological diagnostic applications.

Language: Английский

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