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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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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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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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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Iridium-Catalyzed Cyclative Indenylation and Dienylation through Sequential B(4)–C Bond Formation, Cyclization, and Elimination from o-Carboranes and Propargyl Alcohols

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(22), P. 9890 - 9895

Published: May 12, 2020

Described herein is the first iridium-catalyzed cyclative indenylation through sequential B(4)–C and intramolecular C–C bond formation from o-carboranes propargyl alcohols, leading to of B(4)-indenylated with excellent regioselectivity via direct B–H activation. Moreover, regioselective 1,3-dienylation has been accessed activation, dehydration, decarboxylation, producing B(4)-dienylated o-carboranes.

Language: Английский

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Old Key Opens the Lock in Carborane: The in Situ NHC-Palladium Catalytic System for Selective Arylation of B(3,6)–H Bonds of o-Carboranes via B–H Activation

Organic Letters, Journal Year: 2019, Volume and Issue: 21(22), P. 9276 - 9279

Published: Nov. 5, 2019

An efficient in situ Pd-NHC catalytic system for regioselective arylation of B(3,6)-H bonds o-carborane has been developed the first time. A series symmetric and unsymmetric 3,6-diaryl-o-carboranes anchored with active groups have synthesized moderate to good yields under mild conditions. This work offers an protocol selective activation important value design coupling reactions functionalization o-carboranes.

Language: Английский

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Pd‐Catalyzed Selective Bifunctionalization of 3‐Iodo‐o‐Carborane by Pd Migration

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(12), P. 4851 - 4855

Published: Dec. 25, 2019

Abstract A palladium‐catalyzed highly selective 3,4‐bifunctionalization of 3‐I‐ o ‐carborane has been developed, leading to the preparation 3‐alkenyl‐4‐R‐ ‐carboranes (R=alkyl, alkynyl, aryl, allyl, CN, and amido) in high excellent yields. This protocol combines sequential activation cage B(3)−I B(4)−H bonds by Pd migration from exo ‐alkenyl sp 2 C B(4), which is driven thermodynamic force. represents a brand‐new strategy for bifunctionalization carboranes with two different substituents.

Language: Английский

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Regioselective B(3,4)–H arylation of o-carboranes by weak amide coordination at room temperature

Chemical Science, Journal Year: 2020, Volume and Issue: 11(39), P. 10764 - 10769

Published: Jan. 1, 2020

B–H: site-selective B(3,4)–H arylations were accomplished at room temperature by versatile palladium catalysis enabled weakly coordinating amides.

Language: Английский

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Electrochemical Cage Activation of Carboranes

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

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