Transient Directing Groups for Transformative C–H Activation by Synergistic Metal Catalysis

Chem, Год журнала: 2017, Номер 4(2), С. 199 - 222

Опубликована: Дек. 21, 2017

Язык: Английский

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HFIP in Organic Synthesis

Chemical Reviews, Год журнала: 2022, Номер 122(15), С. 12544 - 12747

Опубликована: Июль 17, 2022

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) is a polar, strongly hydrogen bond-donating solvent that has found numerous uses in organic synthesis due to its ability stabilize ionic species, transfer protons, and engage range of other intermolecular interactions. The use this exponentially increased the past decade become choice some areas, such as C–H functionalization chemistry. In review, following brief history HFIP an overview physical properties, literature examples reactions using or additive are presented, emphasizing effect each reaction.

Язык: Английский

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Controlled functionalization ofo-carboraneviatransition metal catalyzed B–H activation

Chemical Society Reviews, Год журнала: 2019, Номер 48(13), С. 3660 - 3673

Опубликована: Янв. 1, 2019

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

Язык: Английский

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Aggregation‐Induced Electrochemiluminescence of Carboranyl Carbazoles in Aqueous Media

Angewandte Chemie International Edition, Год журнала: 2019, Номер 58(10), С. 3162 - 3166

Опубликована: Янв. 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.

Язык: Английский

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

Accounts of Chemical Research, Год журнала: 2021, Номер 54(21), С. 4065 - 4079

Опубликована: Окт. 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.

Язык: 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, Год журнала: 2018, Номер 16(25), С. 4582 - 4595

Опубликована: Янв. 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.

Язык: Английский

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Transition‐Metal‐Catalyzed Selective Cage B−H Functionalization of o‐Carboranes

Chemistry - A European Journal, Год журнала: 2017, Номер 24(12), С. 2795 - 2805

Опубликована: Ноя. 17, 2017

Abstract Carboranes are a class of carbon–boron molecular clusters with unusual thermal and chemical stabilities. They have been proved as very useful building blocks in supramolecular design, optoelectronics, nanomaterials, boron neutron capture therapy agents organometallic/coordination chemistry. Thus, the functionalization o ‐carboranes has received growing interests. Over past decades, most works this area focused on cage carbon weakly acidic C−H proton can be readily deprotonated by strong bases. In sharp contrast, selective B−H activation/functionalization among chemically similar ten vertices is challenging. Considering differences electron density bonds ‐carborane nature transition metal complexes, we tackled selectivity issue means organometallic Our strategy follows: using electron‐rich catalysts for electron‐deficient B(3,6)−H (bonded to both CH vertices); transition‐metal relatively B(8,9,10,12)−H (with no bonding combination directing groups electrophilic B(4,5,7,11)−H only one vertex). Successful applications such result preparation large variety B‐functionalized carboranes regioselective catalytic manner, which inaccessible other means. It believed that field progresses, expected synthesized, results detailed concept article will further these efforts.

Язык: Английский

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Palladium-catalyzed enantioselective C(sp²)–H arylation of ferrocenyl ketones enabled by a chiral transient directing group

Chemical Communications, Год журнала: 2017, Номер 54(6), С. 689 - 692

Опубликована: Дек. 21, 2017

Palladium-catalyzed enantioselective C(sp2)-H activation of ferrocenyl ketones is achieved through utilizing catalytic, inexpensive l-tert-leucine as a chiral transient directing group. The transformation allows rapid access to ferrocene scaffolds simultaneously possessing planar- and stereogenic central chirality, widely applied in the ferrocene-based ligand families.

Язык: Английский

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Transient‐Ligand‐Enabled ortho ‐Arylation of Five‐Membered Heterocycles: Facile Access to Mechanochromic Materials

Angewandte Chemie International Edition, Год журнала: 2018, Номер 57(13), С. 3401 - 3405

Опубликована: Янв. 30, 2018

Abstract Reported herein is the first example of a direct arylation heteroarenes by transient‐ligand‐directed strategy without need to construct and deconstruct directing group. A wide range undergoes coupling with diverse aryl iodides assemble large library highly selective functionalized 3‐arylthiophene‐2‐carbaldehydes. This route provides an opportunity rapidly access new mechanofluorochromic materials. Moreover, novel for mechanochromic luminogens chromism trends red‐ blue‐shifts has been disclosed time facile functional‐group modifications common structural core.

Язык: 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, Год журнала: 2018, Номер 140(42), С. 13798 - 13807

Опубликована: Сен. 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.

Язык: Английский

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