C–H Activation: Toward Sustainability and Applications

ACS Central Science, Год журнала: 2021, Номер 7(2), С. 245 - 261

Опубликована: Фев. 2, 2021

Since the definition of "12 Principles Green Chemistry" more than 20 years ago, chemists have become increasingly mindful need to conserve natural resources and protect environment through judicious choice synthetic routes materials. The direct activation functionalization C–H bonds, bypassing intermediate functional group installation is, in abstracto, step atom economic, but numerous factors still hinder sustainability large-scale applications. In this Outlook, we highlight research areas seeking overcome challenges activation: pursuit abundant metal catalysts, avoidance static directing groups, replacement oxidants, introduction bioderived solvents. We close by examining progress made subfield aryl borylation from its origins, highly efficient precious Ir-based systems, emerging 3d catalysts. future growth field will depend on industrial uptake, thus urge researchers strive toward sustainable activation.

Язык: Английский

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Asymmetric intermolecular allylic C–H amination of alkenes with aliphatic amines

Science, Год журнала: 2022, Номер 378(6625), С. 1207 - 1213

Опубликована: Дек. 15, 2022

Aliphatic allylic amines are found in a great variety of complex and biorelevant molecules. The direct C-H amination alkenes serves as the most straightforward method toward these motifs. However, use widely available internal with aliphatic this transformation remains synthetic challenge. In particular, palladium catalysis faces twin challenges inefficient coordination Pd(II) to but excessively tight therefore inhibitory by basic amines. We report general solution problems. developed protocol, contrast classical Pd(II/0) scenario, operates through blue light-induced Pd(0/I/II) manifold mild aryl bromide oxidant. This open-shell approach also enables enantio- diastereoselective amination.

Язык: Английский

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Direct Allylic C(sp³)−H and Vinylic C(sp²)−H Thiolation with Hydrogen Evolution by Quantum Dots and Visible Light

Angewandte Chemie International Edition, Год журнала: 2021, Номер 60(21), С. 11779 - 11783

Опубликована: Март 4, 2021

Abstract Direct allylic C−H thiolation is straightforward for C(sp 3 )−S bond formation. However, strong interactions between thiol and transition metal catalysts lead to deactivation of the catalytic cycle or oxidation sulfur atom under oxidative condition. Thus, direct )−H has proved difficult. Represented herein an exceptional direct, efficient, atom‐ step‐economic S−H visible light irradiation. Radical trapping experiments electron paramagnetic resonance (EPR) spectroscopy identified radical thiyl generated on surface photocatalyst quantum dots (QDs). The C−S formation does not require external oxidants initiators, hydrogen (H 2 ) produced as byproduct. When vinylic was used instead bond, radical‐radical cross‐coupling achieved with liberation H . Such a unique transformation opens up door toward coupling valuable organosulfur chemistry.

Язык: Английский

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Metal-free allylic C–H nitrogenation, oxygenation, and carbonation of alkenes by thianthrenation

Chemical Science, Год журнала: 2021, Номер 13(4), С. 1003 - 1008

Опубликована: Дек. 20, 2021

Selective functionalization of allylic C-H bonds into other chemical is among the most straightforward and attractive, yet challenging transformations. Herein, a transition-metal-free protocol for direct nitrogenation, oxygenation, carbonation alkenes by thianthrenation was developed. This operationally simple allows unified amination, esterification, etherification, arylation vinyl thianthrenium salts. Notably, reaction furnishes multialkyl substituted amines, ammonium salts, sulfonyl amides, esters, ethers in good yields. The proceeds under mild conditions with excellent functional group tolerance could be applied to late-stage allylation natural products, drug molecules peptides chemoselectivity.

Язык: Английский

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Tailored cobalt-salen complexes enable electrocatalytic intramolecular allylic C–H functionalizations

Nature Communications, Год журнала: 2021, Номер 12(1)

Опубликована: Июнь 18, 2021

Abstract Oxidative allylic C–H functionalization is a powerful tool to streamline organic synthesis as it minimizes the need for functional group activation and generates alkenyl-substituted products amenable further chemical modifications. The intramolecular variants can be used construct functionalized ring structures but remain limited in scope by their frequent requirement noble metal catalysts stoichiometric oxidants. Here we report an oxidant-free, electrocatalytic approach achieve oxidative amination alkylation employing tailored cobalt-salen complexes catalysts. These reactions proceed through radical mechanism display broad tolerance of groups alkene substitution patterns, allowing efficient coupling di-, tri- even tetrasubstituted alkenes with N- C-nucleophiles furnish high-value heterocyclic carbocyclic structures.

Язык: Английский

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Enantioselective C−H functionalization reactions enabled by cobalt catalysis

Chem Catalysis, Год журнала: 2022, Номер 2(11), С. 2965 - 2985

Опубликована: Сен. 16, 2022

Язык: Английский

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Palladium-Catalyzed Oxidative Amination of Unactivated Olefins with Primary Aliphatic Amines

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(17), С. 9448 - 9453

Опубликована: Апрель 13, 2023

Direct coupling of unactivated olefins with primary alkylamines is considered to be an efficient but unknown method for the construction complex amines. Herein we report a catalytic intermolecular oxidative amination aliphatic amines based on combination palladium catalyst, bidentate phosphine ligand, and duroquinone. A range secondary allylic were obtained in good yields excellent regio- stereoselectivity. Mechanistic control experiments revealed that reaction proceeds by C(sp3)-H activation nucleophilic amination. The utility protocol further demonstrated late-stage modification streamlined synthesis drug molecules.

Язык: Английский

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Designed Iron Catalysts for Allylic C−H Functionalization of Propylene and Simple Olefins

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(10)

Опубликована: Янв. 9, 2023

Abstract Propylene gas is produced worldwide by steam cracking on million‐metric‐ton scale per year. It serves as a valuable starting material for π‐bond functionalization but rarely applied in transition metal‐catalyzed allylic C−H fine chemical synthesis. Herein, we report that newly‐developed cationic cyclopentadienyliron dicarbonyl complex allows the conversion of propylene to its C−C bond coupling products under catalytic conditions. This approach was also found applicable simple α‐olefins with distinctive branched selectivity. Experimental and computational mechanistic studies supported deprotonation metal‐coordinated alkene turnover‐limiting step led insights into multifaceted roles newly designed ligand promoting enhanced reactivity stereoselectivity.

Язык: Английский

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Alkene Thianthrenation Unlocks Diverse Cation Synthons: Recent Progress and New Opportunities

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(16)

Опубликована: Фев. 8, 2024

Oxidative alkene functionalization reactions are a fundamental class of complexity-building organic transformations. However, the majority established approaches rely on electrophilic reagents that limit diversity groups can be installed. Recent advances have new approach instead relies transformation alkenes into thianthrene-derived cationic electrophiles. These linchpin intermediates generated selectively and undergo diverse array mechanistically distinct with abundant nucleophiles. Taken together, this unlocks suite net oxidative transformations been elusive using conventional strategies. This Minireview describes these is organized around three synthons formally accessible from via thianthrenation: 1) alkenyl cations; 2) vicinal dications; 3) allyl cations. Throughout Minireview, we illustrate how thianthrenium salts address key limitations endemic to classic alkene-derived electrophiles highlight mechanistic origins distinctions wherever possible.

Язык: Английский

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Use of Strain-Release for the Diastereoselective Construction of Quaternary Carbon Centers

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(20), С. 7648 - 7654

Опубликована: Май 11, 2021

Herein, we describe the formation of quaternary carbon centers with excellent diastereoselectivity via a strain-release protocol. An organometallic species is generated by Cp*Rh(III)-catalyzed C–H activation, which then coupled strained bicyclobutanes (BCBs) and prochiral electrophile in three-component reaction. This work illustrates rare example BCBs transition metal catalysis demonstrates their broad potential to access novel reaction pathways. The method developed exhibits ample functional group tolerance, products can be further transformed into valuable α-quaternary β-lactones. Preliminary mechanistic investigations suggest twofold C–C bond cleavage sequence involving σ-bond insertion an ensuing β-carbon elimination event.

Язык: Английский

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