Hydrogen atom abstraction
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Enantioselective cyanation of benzylic C–H bonds via copper-catalyzed radical relay Open
Direct methods for stereoselective functionalization of sp 3 -hybridized carbon–hydrogen [C(sp 3 )–H] bonds in complex organic molecules could facilitate much more efficient preparation of therapeutics and agrochemicals. Here, we report a …
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Selective Hydrogen Atom Abstraction through Induced Bond Polarization: Direct α‐Arylation of Alcohols through Photoredox, HAT, and Nickel Catalysis Open
The combination of nickel metallaphotoredox catalysis, hydrogen atom transfer catalysis, and a Lewis acid activation mode, has led to the development of an arylation method for the selective functionalization of alcohol α‐hydroxy C−H bonds…
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Thioetherification via Photoredox/Nickel Dual Catalysis Open
Hypervalent alkylsilicates represent new and readily accessible precursors for the generation of alkyl radicals under photoredox conditions. Alkyl radicals generated from such silicates serve as effective hydrogen atom abstractors from thi…
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Directed β C–H Amination of Alcohols via Radical Relay Chaperones Open
A radical-mediated strategy for β C-H amination of alcohols has been developed. This approach employs a radical relay chaperone, which serves as a traceless director that facilitates selective C-H functionalization via 1,5-hydrogen atom tr…
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A cross-dehydrogenative C(sp3)−H heteroarylation via photo-induced catalytic chlorine radical generation Open
Hydrogen atom abstraction (HAT) from C( sp 3 )–H bonds of naturally abundant alkanes for alkyl radical generation represents a promising yet underexplored strategy in the alkylation reaction designs since involving stoichiometric oxidants,…
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Characterization of Iron-Imido Species Relevant for <i>N</i>-Group Transfer Chemistry Open
A sterically accessible tert-butyl-substituted dipyrrinato di-iron(II) complex [((tBu)L)FeCl]2 possessing two bridging chloride atoms was synthesized from the previously reported solvento adduct. Upon treatment with aryl azides, the format…
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Frontier Molecular Orbital Contributions to Chlorination versus Hydroxylation Selectivity in the Non-Heme Iron Halogenase SyrB2 Open
The ability of an FeIV═O intermediate in SyrB2 to perform chlorination versus hydroxylation was computationally evaluated for different substrates that had been studied experimentally. The π-trajectory for H atom abstraction (FeIV═O orient…
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Asymmetric Induction and Enantiodivergence in Catalytic Radical C–H Amination via Enantiodifferentiative H-Atom Abstraction and Stereoretentive Radical Substitution Open
Control of enantioselectivity remains a major challenge in radical chemistry. The emergence of metalloradical catalysis (MRC) offers a conceptually new strategy for addressing this and other outstanding issues. Through the employment of D2…
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Anthraquinones as Photoredox Catalysts for the Reductive Activation of Aryl Halides Open
Quinones are ubiquitous in nature as structural motifs in natural products and redox mediators in biological electron‐transfer processes. Although their oxidation properties have already been used widely in chemical and photochemical react…
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Visualizing the Reaction Cycle in an Iron(II)- and 2-(Oxo)-glutarate-Dependent Hydroxylase Open
Iron(II)- and 2-(oxo)-glutarate-dependent oxygenases catalyze diverse oxidative transformations that are often initiated by abstraction of hydrogen from carbon by iron(IV)-oxo (ferryl) complexes. Control of the relative orientation of the …
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Halogen-atom and group transfer reactivity enabled by hydrogen tunneling Open
The generation of carbon radicals by halogen-atom and group transfer reactions is generally achieved using tin and silicon reagents that maximize the interplay of enthalpic (thermodynamic) and polar (kinetic) effects. In this work, we demo…
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Flavones’ and Flavonols’ Antiradical Structure–Activity Relationship—A Quantum Chemical Study Open
Flavonoids are known for their antiradical capacity, and this ability is strongly structure-dependent. In this research, the activity of flavones and flavonols in a water solvent was studied with the density functional theory methods. Thes…
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Origin of the Enhanced Reactivity of μ-Nitrido-Bridged Diiron(IV)-Oxo Porphyrinoid Complexes over Cytochrome P450 Compound I Open
µ-Nitrido bridged diiron porphyrins and phthalocyanines are known to be efficient oxidants that are able to oxidize some of the strongest C–H bonds in nature, such as the one in methane. The origin of their catalytic efficiency is poorly u…
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Reactivity control of a photocatalytic system by changing the light intensity Open
By using simple optics such as a lens, switching between one- and two-photon driven reaction mechanisms became feasible, which allows the control over the main products of photochemical reactions.
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Mechanisms for Hydrogen-Atom Abstraction by Mononuclear Copper(III) Cores: Hydrogen-Atom Transfer or Concerted Proton-Coupled Electron Transfer? Open
In a possibly biomimetic fashion, formally copper(III)-oxygen complexes LCu(III)-OH (1) and LCu(III)-OOCm (2) (L2- = N,N'-bis(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamide, Cm = α,α-dimethylbenzyl) have been shown to activate X-H bonds …
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Why the Reactive Oxygen Species of the Fenton Reaction Switches from Oxoiron(IV) Species to Hydroxyl Radical in Phosphate Buffer Solutions? A Computational Rationale Open
It has been shown that the major reactive oxygen species (ROS) generated by the aqueous reaction of Fe(II) and H2O2 (i.e., the Fenton reaction) are high-valent oxoiron(IV) species, whereas the hydroxyl radical plays a role only in very aci…
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δ-C–H Mono- and Dihalogenation of Alcohols Open
Alkoxy radicals have long been known to enable remote C-H functionalization via 1,5-hydrogen atom abstraction. However, methods for their generation traditionally have relied upon highly oxidizing metals, ultraviolet radiation, or preforme…
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Selective Hydrogen Atom Abstraction from Dihydroflavonol by a Nonheme Iron Center Is the Key Step in the Enzymatic Flavonol Synthesis and Avoids Byproducts Open
The plant non-heme iron dioxygenase flavonol synthase performs a regioselective desaturation reaction as part of the biosynthesis of the signaling molecule flavonol that triggers the growing of leaves and flowers. These compounds also have…
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Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction Open
Catalysts for the oxidation of NH 3 are critical for the utilization of NH 3 as a large‐scale energy carrier. Molecular catalysts capable of oxidizing NH 3 to N 2 are rare. This report describes the use of [Cp*Ru(P t Bu 2 N Ph 2 )( 15 NH 3…
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Catalysis by the Non-Heme Iron(II) Histone Demethylase PHF8 Involves Iron Center Rearrangement and Conformational Modulation of Substrate Orientation Open
PHF8 (KDM7B) is a human non-heme 2-oxoglutarate (2OG) JmjC domain oxygenase that catalyzes the demethylation of the di/mono-Nε-methylated K9 residue of histone H3. Altered PHF8 activity is linked to genetic diseases and cancer; thus, it is…
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Copper-Catalyzed Intermolecular Functionalization of Unactivated C(sp<sup>3</sup>)–H Bonds and Aliphatic Carboxylic Acids Open
Intermolecular functionalization of C(sp3)-H bonds and aliphatic carboxylic acids enables the efficient synthesis of high value-added organic compounds from readily available starting materials. Although methods involving hydrogen atom tra…
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Mechanism of O<sub>2</sub>activation and substrate hydroxylation in noncoupled binuclear copper monooxygenases Open
Significance Nature has evolved several strategies for using dioxygen (O 2 ) for chemical oxidations. These enzymatic processes typically use metal cofactors to impart selectivity and minimize production of deleterious reactive oxygen spec…
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Environmental implications of superoxide radicals: From natural processes to engineering applications Open
The roles of superoxide radical (O2•-) in the domains of physiological, physical, and material chemistry are becoming increasingly recognized. Although extensive efforts have been directed to understand O2•- functions in diverse aquatic sy…
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Aliphatic C–H Functionalization Using Pyridine <i>N</i>-Oxides as H-Atom Abstraction Agents Open
The alkylation and heteroarylation of unactivated tertiary, secondary, and primary C(sp3)-H bonds was achieved by employing an acridinium photoredox catalyst along with readily available pyridine Noxides as hydrogen atom transfer (HAT) pre…
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New Catalytic Radical Process Involving 1,4-Hydrogen Atom Abstraction: Asymmetric Construction of Cyclobutanones Open
While alkyl radicals have been well demonstrated to undergo both 1,5- and 1,6-hydrogen atom abstraction (HAA) reactions, 1,4-HAA is typically a challenging process both entropically and enthalpically. Consequently, chemical transformations…
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Hydrogen‐Abstraction/Acetylene‐Addition Exposed Open
Polycyclic aromatic hydrocarbons (PAHs) are omnipresent in the interstellar medium (ISM) and also in carbonaceous meteorites (CM) such as Murchison. However, the basic reaction routes leading to the formation of even the simplest PAH—napht…
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Fast Hydrogen Atom Abstraction by a Hydroxo Iron(III) Porphyrazine Open
A reactive hydroxoferric porphyrazine complex, [(PyPz)FeIII(OH) (OH2)]4+ (1, PyPz = tetramethyl-2,3-pyridino porphyrazine), has been prepared via one-electron oxidation of the corresponding ferrous species [(PyPz)FeII(OH2)2]4+ (2). Electro…
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Tetranuclear Manganese Models of the OEC Displaying Hydrogen Bonding Interactions: Application to Electrocatalytic Water Oxidation to Hydrogen Peroxide Open
Toward the development of structural and functional models of the oxygen evolving complex (OEC) of photosystem II, we report the synthesis of site-differentiated tetranuclear manganese complexes featuring three six-coordinate and one five-…
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Visible Light‐Mediated Dearomative Hydrogen Atom Abstraction/ Cyclization Cascade of Indoles Open
The photochemical synthesis of yet unknown 2‐oxospiro[azetidine‐3,3′‐indolines] (17 examples, 80–95 % yield), 2,4‐dioxospiro[azetidine‐3,3′‐indolines] (eight examples, 87–97 % yield), and 1‐oxo‐1,3‐dihydrospiro[indene‐2,3′‐indolines] (17 e…
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Chemical Non‐Innocence of an Aliphatic PNP Pincer Ligand Open
The synthesis of the divinylamido PNP nickel(II) complex [NiBr{N(CHCHP t Bu 2 ) 2 }] is reported. This compound exhibits reversible, ligand‐centered oxidation and protonation reactions. The resulting pincer chemical non‐innocence can be ut…