Methylene C(sp³)–H Arylation of Aliphatic Ketones Using a Transient Directing Group

ACS Catalysis, Journal Year: 2017, Volume and Issue: 7(10), P. 6938 - 6941

Published: Sept. 13, 2017

Palladium-catalyzed methylene β-C(sp

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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Ligand‐Controlled Direct γ‐C−H Arylation of Aldehydes

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(8), P. 3078 - 3082

Published: Nov. 28, 2019

Abstract The first example of Pd II ‐catalyzed γ‐C(sp 3 )−H functionalization aliphatic and benzoheteroaryl aldehydes has been developed using a transient ligand an external ligand, concurrently. A wide array γ‐arylated were readily accessed without preinstalling internal directing groups. catalytic mechanism was studied by performing deuterium‐labelling experiments, which indicated that the bond cleavage is rate‐limiting step during reaction process. This could be performed on gram scale, also demonstrated its potential application in synthesis new mechanofluorochromic materials with blue‐shifted mechanochromic properties.

Language: Английский

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Palladium Catalyzed Regioselective C4‐Arylation and Olefination of Indoles and Azaindoles

Advanced Synthesis & Catalysis, Journal Year: 2019, Volume and Issue: 361(6), P. 1441 - 1446

Published: Jan. 2, 2019

Abstract A convergent strategy for the synthesis of biologically relevant C4‐substituted indole scaffolds was demonstrated using Pd(II)‐catalyzed remote C−H functionalization indoles and azaindoles. The reaction displays high regioselectivity C4‐position indole‐3‐carbaldehydes glycine as an inexpensive transient directing group. Notable features this transformation include selective formation six‐membered palladacyle excellent functional group tolerance. magnified image

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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Imine as a linchpin approach for meta-C–H functionalization

Nature Communications, Journal Year: 2021, Volume and Issue: 12(1)

Published: March 2, 2021

Despite the widespread applications of C-H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing groups (DGs) served as ancillary ligands to ensure ortho-, meta- and para-C-H functionalization over last two decades. These covalently linked DGs necessitate extra steps for single functionalization: introduction DG prior activation removal post-functionalization. Here we report temporary group (TDG) meta-C-H via reversible imine formation. By overruling facile ortho-C-H bond by imine-N atom, suitably designed pyrimidine-based TDG successfully delivered selective meta-C-C Application this strategy streamlining synthesis complex organic molecules without any necessary pre-functionalization at meta position has been explored.

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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Facile Construction of New Hybrid Conjugation via Boron Cage Extension

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(6), P. 3577 - 3587

Published: Feb. 6, 2023

Aromatic polycyclic systems have been extensively utilized as structural subunits for the preparation of various functional molecules. Currently, aromatics-based are predominantly generated from extension two-dimensional (2D) aromatic rings. In contrast, compounds based on three-dimensional (3D) aromatics such boron clusters less studied. Here, we report three types cluster-cored tricyclic molecular systems, which constructed a 2D ring, 3D nido-carborane, and an alkyne. These new can be facilely accessed by Pd-catalyzed B-H activation subsequent cascade heteroannulation carborane pyridine with alkyne in isolated yield up to 85% under mild conditions without any additives. Computational results indicate that newly ring fusion carborane, pyridyl is non-aromatic. However, not only leads 1H chemical shift considerably downfield shifted owing strong diatropic current embedded but also devotes new/improved physicochemical properties including increased thermal stability, emergence absorption band, largely red-shifted emission band enhanced efficiency. Besides, number bright, color-tunable solid emitters spanning over all visible light obtained absolute luminescence efficiency 61%, contrast aggregation-caused quenching of, e.g., Rhodamine B containing 2D-aromatics-fused structure. This work demonstrates hybrid conjugated might promising scaffolds construction

Language: Английский

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Direct B–H Functionalization of Icosahedral Carboranes via Hydrogen Atom Transfer

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7638 - 7647

Published: March 22, 2023

The efficient and selective functionalization of icosahedral carboranes (C2B10H12) at the boron vertexes is a long-standing challenge owing to presence 10 inert B-H bonds in similar chemical environment. Herein, we report new reaction paradigm for direct via homolysis enabled by nitrogen-centered radical-mediated hydrogen atom transfer (HAT) strategy. Both HAT process carborane bond resulting boron-centered carboranyl radical intermediate have been confirmed experimentally. occurs most electron-rich vertex with lowest dissociation energy (BDE). Using this strategy, diverse derivatization, including thiolation, selenation, alkynylation, alkenylation, cyanation, halogenation, achieved satisfactory yields under photoinitiated condition metal-free redox-neutral fashion. Moreover, synthetic utility current protocol was also demonstrated both scale-up construction carborane-based functional molecules. Therefore, methodology opens pathway functionalization, which distinct from heterolytic mechanism traditional strategies.

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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