Catalysis with Diboron(4)/Pyridine: Application to the Broad-Scope [3 + 2] Cycloaddition of Cyclopropanes and Alkenes

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(19), С. 8870 - 8882

Опубликована: Май 9, 2022

In contrast to the extensive but non-recyclable use of tetraalkoxydiboron(4) compounds as stoichiometric reagents in diverse reactions, this article reports an atom-economical reaction using a commercial diboron(4) catalyst. The key success was designing catalytic cycle for radical [3 + 2] cycloaddition involving pyridine cocatalyst generate from catalyst and reversibly mediate transfer boronyl radicals. comparison with known transition metal-based catalysts, current features not only metal-free conditions, inexpensive stable simple operation also remarkably broadened substrate scope. particular, previously unusable cyclopropyl ketones without activating group and/or alkenes 1,2-disubstitution 1,1,2-trisubstitution patterns were successfully used first time. Consequently, challenging cyclopentane various levels substitution (65 examples, 57 new products, up six substituents at all five ring atoms) readily prepared generally high excellent yield diastereoselectivity. applied concise formal synthesis anti-obesity drug building natural product-like complex bridged or spirocyclic compounds. Mechanistic experiments computational investigation support proposed relay catalysis featuring pyridine-assisted Overall, work demonstrates approach catalysts may lead development new, green, efficient metal-like boron-catalyzed organic reactions.

Язык: Английский

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Multiple-fold C–F bond functionalization for the synthesis of (hetero)cyclic compounds: fluorine as a detachable chemical handle

Organic Chemistry Frontiers, Год журнала: 2022, Номер 9(7), С. 2013 - 2055

Опубликована: Янв. 1, 2022

We highlighted the recent advances in field of multiple-fold C–F bond functionalization for synthesis (hetero)cyclic compounds.

Язык: Английский

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Palladium‐Catalyzed Fluorinative Bifunctionalization of Aziridines and Azetidines with gem‐Difluorocyclopropanes

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(42)

Опубликована: Авг. 12, 2023

Abstract An unprecedented Pd‐catalyzed fluorinative bifunctionalization of aziridines and azetidines was successfully developed via regioselective C−C C−F bond cleavage gem‐difluorocyclopropanes, leading to various β,β′‐bisfluorinated amines β,γ‐bisfluorinated amines. This reaction achieved by incorporating a 2‐fluorinated allyl group fluorine atom scissored from gem‐difluorocyclopropane in 100 % economy for the first time. The mechanistic investigations indicated that underwent amine attacking palladium complex generate η 2 ‐coordinated N‐allyl aziridine followed fluoride ligand transfer affording final β‐ γ‐fluorinated

Язык: Английский

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Diborodichloromethane as Versatile Reagent for Chemodivergent Synthesis of gem‐Diborylalkanes

Angewandte Chemie International Edition, Год журнала: 2023, Номер 63(3)

Опубликована: Дек. 8, 2023

Abstract The development of boron reagents is crucial for synthetic chemistry. Herein, we present a scalable and practical synthesis diborodichloromethane (DBDCM) through the reaction trichloromethyllithium with bis(pinacolato)diboron (B 2 pin ). resulting DBDCM reagent serves as basic unit construction various structurally diverse gem ‐diborylalkanes controllable C−Cl functionalizations. Moreover, have developed consecutive tetra‐functionalizations tertiary quaternary carbon containing molecules. use isotopically enriched 13 C‐chloroform 10 B enables C‐DBDCM B‐DBDCM reagents, which are beneficial convenient carbon‐13 boron‐10

Язык: Английский

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Ir-Catalyzed Regioselective Dihydroboration of Thioalkynes toward Gem-Diboryl Thioethers

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(4), С. 2305 - 2314

Опубликована: Янв. 19, 2023

While 1,1-diboryl (gem-diboryl) compounds are valuable synthetic building blocks, currently, related studies have mainly focused on those alkanes without a hetero functional group in the α-position. gem-Diboryl with an α-hetero substituent, though highly versatile, been limitedly accessible and thus rarely utilized. Herein, we developed first α-dihydroboration of heteroalkynes leading to efficient construction gem-diboryl, hetero-, tetra-substituted carbon centers. This straightforward, practical, mild, atom-economic reaction is attractive complement conventional multistep strategy relying deprotonation gem-diborylmethane by strong base. Specifically, [Ir(cod)(OMe)]2 was found be uniquely effective for this process thioalkynes, excellent α-regioselectivity when delivering two boryl groups, which remarkable view many competitive paths including monohydroboration, 1,2-dihydroboration, dehydrodiboration, triboration, tetraboration, etc. Control experiments combined DFT calculations suggested that involves sequential hydroboration events. The second requires higher energy barrier due severe steric repulsion generating congested α-sulfenyl gem-diboryl center, structural motif almost unknown before.

Язык: Английский

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Photouranium-Catalyzed C–F Activation Hydroxylation via Water Splitting

Journal of the American Chemical Society, Год журнала: 2024, Номер unknown

Опубликована: Апрель 9, 2024

The C–F bond is the strongest covalent single (126 kcal/mol) in carbon-centered bonds, which highest electronegativity of fluorine (χ = 4) gives rise to shortest length (1.38 Å) and smallest van der Waals radius (rw 1.47 Å), resulting enormous challenges for activation transformation. Herein, conversion was realized via photouranium-catalyzed hydroxylation unactivated aryl fluorides using water as a hydroxyl source deliver multifunctional phenols under ambient conditions. featured cascade sequences electron transfer (SET)/hydrogen atom (HAT)/oxygen (OAT), highly integrated from excited uranyl cation. *UO22+ prompted splitting mild photoexcitation, caging active oxygen peroxo-bridged manner critical OAT process releasing hydrogen HAT process.

Язык: Английский

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Cu-Catalyzed Regio- and Stereodivergent Chemoselective sp/sp 1,3- and 1,4-Diborylations of CF3-Containing 1,3-Enynes

Chem, Год журнала: 2020, Номер 6(9), С. 2347 - 2363

Опубликована: Июль 23, 2020

Язык: Английский

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Inorganometallics (Transition Metal–Metalloid Complexes) and Catalysis

Chemical Reviews, Год журнала: 2021, Номер 122(3), С. 3996 - 4090

Опубликована: Дек. 30, 2021

While the formation and breaking of transition metal (TM)-carbon bonds plays a pivotal role in catalysis organic compounds, reactivity inorganometallic species, that is, those involving (TM)-metalloid (E) bond, is key importance most conversions metalloid derivatives catalyzed by TM complexes. This Review presents background its development over last 15 years. The results mechanistic studies presented are related to occurrence TM-E TM-H compounds as reactive intermediates catalytic transformations selected metalloids (E = B, Si, Ge, Sn, As, Sb, or Te). illustrates significance inorganometallics following processes: addition metalloid-hydrogen metalloid-metalloid unsaturated compounds; activation functionalization C-H C-X with hydrometalloids bismetalloids; vinylmetalloids, halides, sulfonates; dehydrocoupling hydrometalloids. first on sums up developments methods for synthesis organometalloid their applications advanced part tandem reactions.

Язык: Английский

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Generation of Axially Chiral Fluoroallenes through a Copper-Catalyzed Enantioselective β-Fluoride Elimination

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(34), С. 13759 - 13768

Опубликована: Авг. 16, 2021

Herein we report the copper-catalyzed silylation of propargylic difluorides to generate axially chiral, tetrasubstituted monofluoroallenes in both good yields (27 examples >80%) and enantioselectivities (82-98% ee). Compared previously reported synthetic routes chiral allenes (ACAs) from prochiral substrates, a mechanistically distinct reaction has been developed: enantiodiscrimination between enantiotopic fluorides set an axial stereocenter. DFT calculations vibrational circular dichroism (VCD) suggest that β-fluoride elimination alkenyl copper intermediate likely proceeds through syn-β-fluoride pathway rather than anti-elimination pathway. The effects C1-symmetric Josiphos-derived ligand on reactivity enantioselectivity were investigated. Not only does this showcase species (like their alkyl counterparts) can undergo elimination, but be achieved enantioselective fashion.

Язык: Английский

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Experimental and Computational Studies of the Iron‐Catalyzed Selective and Controllable Defluorosilylation of Unactivated Aliphatic gem‐Difluoroalkenes

Angewandte Chemie International Edition, Год журнала: 2021, Номер 60(18), С. 10211 - 10218

Опубликована: Фев. 8, 2021

The first iron-catalyzed defluorosilylation of unactivated gem-difluoroalkenes was developed, delivering gem-disilylated alkenes and (E)-silylated with excellent efficiency. This protocol features good functional group compatibility regio- stereoselectivity, enabling the late-stage silylation biologically relevant compounds, thus providing opportunities for applications in medicinal chemistry. Preliminary mechanistic studies DFT calculations reveal that a nucleophilic addition elimination second C-F bond might be involved disilylation catalytic system, demonstrating unusual reactivity characteristics iron catalysis.

Язык: Английский

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