Debate of Nucleophilic versus Electrophilic Oxidative Aldehyde Deformylation by Mononuclear Nonheme Iron(III)-Peroxo and Iron(IV)-Oxo Complexes

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Апрель 28, 2025

High-valent iron(IV)-oxo species are fleeting intermediates that perform vital reactions in enzymatic catalysis. In contrast, heme and nonheme iron(III)-peroxo usually act as nucleophiles converted to high-valent iron-oxo for electrophilic oxidation reactions. Herein, we report a study on aldehyde deformylation of 2-phenylpropionaldehyde (2-PPA) its derivatives by complexes bearing tetramethylated cyclam (TMC) analogues, including [FeIII(O2)(12-TMC)]+ (1), [FeIII(O2)(13-TMC)]+ (2), [FeIII(O2)(14-TMC)]+ (3). Reactivity studies employing deuterated substrates, such α-[D1]-2-phenylpropionaldehyde aldehyde-[D]-2-phenylpropionaldehyde, demonstrate 2-PPA the occurs via abstraction stronger C-H atom, rather than expected nucleophilic attack or weaker α-C-H atom Interestingly, preference is retained during complexes, i.e., [FeIV(O)(13-TMC)]2+ (4) [FeIV(O)(N4Py)]2+ (5). DFT calculations reproduce experimental trends reactivity reveal peroxide O-O bond cleaved form an iron(III)-dioxyl conducts abstraction; this chemoselectivity achieved through stabilizing noncovalent interactions between oxidants aromatic ring substrate positions close proximity FeIII-O2/FeIV═O cores. These new theoretical findings together with previous demonstrations ability 1-3 hydrogen transfer, oxygen cis-dihydroxylation highlight cores not inherently can have more important functions chemical biological reactions, acting transient en route metal-oxo intermediates.

Язык: Английский

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Iron-oxygen intermediates in catalyst systems non-heme Fe complex/H2O2(AcOOH)/RC(O)OH and their reactivity in oxidative dearomatization reactions

Inorganic Chemistry Communications, Год журнала: 2025, Номер unknown, С. 114687 - 114687

Опубликована: Май 1, 2025

Язык: Английский

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Asymmetric Epoxidation vs syn-Hydroxy-Acyloxylation of Olefins in the Presence of Sterically Demanding Nonheme Manganese Complexes

ACS Catalysis, Год журнала: 2023, Номер 14(1), С. 498 - 507

Опубликована: Дек. 22, 2023

Herewith, we present another facet of the versatile catalytic reactivity bulky bis-amino-bis-pyridylmethyl Mn complexes: besides highly enantioselective (up to 99% ee) epoxidation, benzhydryl-substituted catalysts have been found convert olefinic substrates into products syn-addition C═C bond, hydroxy-carboxylates, that can prevail under certain conditions. The mechanism syn-hydroxy-acyloxylation is discussed, with data obtained providing evidence in favor so far lacking direct OH and OC(O)R transfer from high-valent active species group. Such a conceptually reminiscent Rieske dioxygenases catalyze 1,2-dihydroxylation bonds, simultaneously incorporating two cis-ligands reactive metal center resulting diol syn-selective fashion.

Язык: Английский

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C–H Bond Oxidation by Mn^IV–Oxo Complexes: Hydrogen-Atom Tunneling and Multistate Reactivity

Inorganic Chemistry, Год журнала: 2024, Номер 63(17), С. 7754 - 7769

Опубликована: Апрель 16, 2024

The reactivity of six MnIV–oxo complexes in C–H bond oxidation has been examined using a combination kinetic experiments and computational methods. Variable-temperature studies the 9,10-dihydroanthracene (DHA) ethylbenzene by these yielded activation parameters suitable for evaluating electronic structure computations. Complementary deuterated DHA provided evidence hydrogen-atom tunneling all complexes. These results are accordance with Bell model, where occurs near top transition-state barrier. Density functional theory (DFT) DLPNO–CCSD(T1) computations were performed three to probe previously predicted multistate model. DFT thermal crossing from 4B1 ground state 4E along reaction coordinate. calculations further confirm that transition offers lower energy barrier, reinforcing model We discuss how this can be reconciled recent revealed kinetics set well-predicted on basis thermodynamic driving force reactions.

Язык: Английский

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tert‐Butyl as a Functional Group: Non‐Directed Catalytic Hydroxylation of Sterically Congested Primary C−H Bonds

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(28)

Опубликована: Май 1, 2024

Abstract The tert ‐butyl group is a common aliphatic motif extensively employed to implement steric congestion and conformational rigidity in organic organometallic molecules. Because of the combination high bond dissociation energy (~100 kcal mol −1 ) limited accessibility, absence directing groups, neither radical nor approaches are effective for chemical modification C−H bonds. Herein we overcome these limits by employing highly electrophilic manganese catalyst, [Mn( CF3 bpeb)(OTf) 2 ], that operates strong hydrogen donor solvent nonafluoro‐ alcohol (NFTBA) catalytically activates peroxide generate powerful manganese‐oxo species effectively oxidizes Leveraging on interplay steric, electronic, medium torsional effects, site‐selective product chemoselective hydroxylation accomplished with broad reaction scope, delivering primary alcohols as largely dominant products preparative yields. Late‐stage at sites demonstrated 6 densely functionalized molecules pharmaceutical interest. This work uncovers novel disconnection approach, harnessing potential functional strategic synthetic planning complex molecular architectures.

Язык: Английский

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