Palladium-Catalyzed Ligand-Controlled Switchable Hetero-(5 + 3)/Enantioselective [2σ+2σ] Cycloadditions of Bicyclobutanes with Vinyl Oxiranes

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(29), С. 19621 - 19628

Опубликована: Май 13, 2024

For nearly 60 years, significant research efforts have been focused on developing strategies for the cycloaddition of bicyclobutanes (BCBs). However, higher-order and catalytic asymmetric BCBs long-standing formidable challenges. Here, we report Pd-catalyzed ligand-controlled, tunable cycloadditions divergent synthesis bridged bicyclic frameworks. The dppb ligand facilitates formal (5+3) vinyl oxiranes, yielding valuable eight-membered ethers with scaffolds in 100% regioselectivity. Cy-DPEphos promotes selective hetero-[2σ+2σ] to access pharmacologically important 2-oxabicyclo[3.1.1]heptane (O-BCHeps). Furthermore, corresponding O-BCHeps 94–99% ee has achieved using chiral (S)-DTBM-Segphos, representing first cross-dimerization two strained rings. obtained are promising bioisosteres ortho-substituted benzenes.

Язык: Английский

---

Enantioselective Reductive Cross-Couplings of Olefins by Merging Electrochemistry with Nickel Catalysis

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(44), С. 23910 - 23917

Опубликована: Окт. 26, 2023

The merger of electrochemistry and transition metal catalysis has emerged as a powerful tool to join two electrophiles in an enantioselective manner. However, the development electroreductive cross-couplings olefins remains challenge. Inspired by advantages synergistic use with nickel catalysis, we present here Ni-catalyzed cross-coupling acrylates aryl halides alkyl bromides, which affords chiral α-aryl carbonyls good excellent enantioselectivity. Additionally, this catalytic reaction can be applied (hetero)aryl chlorides, is difficult achieve other methods. combination cyclic voltammetry analysis electrode potential studies suggests that NiI species activates oxidative addition bromides single-electron transfer.

Язык: Английский

---

Switching between the [2π+2σ] and Hetero‐[4π+2σ] Cycloaddition Reactivity of Bicyclobutanes with Lewis Acid Catalysts Enables the Synthesis of Spirocycles and Bridged Heterocycles

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(29)

Опубликована: Май 11, 2024

Abstract The exploration of the complex chemical diversity bicyclo[n.1.1]alkanes and their use as benzene bioisosteres has garnered significant attention over past two decades. Regiodivergent syntheses thiabicyclo[4.1.1]octanes (S‐BCOs) highly substituted bicyclo[2.1.1]hexanes (BCHs) using a Lewis acid‐catalyzed formal cycloaddition bicyclobutanes (BCBs) 3‐benzylideneindoline‐2‐thione derivatives have been established. first hetero‐(4+3) BCBs, catalyzed by Zn(OTf) 2 , was achieved with broad substrate scope under mild conditions. In contrast, less electrophilic BCB ester undergoes Sc(OTf) 3 ‐catalyzed [2π+2σ] reaction 1,1,2‐trisubstituted alkenes, yielding BCHs spirocyclic quaternary carbon center. Control experiments preliminary theoretical calculations suggest that diastereoselective product formation may involve concerted between zwitterionic intermediate E ‐1,1,2‐trisubstituted alkenes. Additionally, nucleophilic ring‐opening mechanism.

Язык: Английский

---

Photoredox/Cr-catalyzed enantioselective radical-polar crossover transformation via C-H functionalization

Nature Communications, Год журнала: 2025, Номер 16(1)

Опубликована: Фев. 4, 2025

Asymmetric multicomponent reactions that aim to control multiple chiral centers with high selectivity in a single step remain an on-gonging challenge. The realm of enantioselective radical-polar crossover transformation achieved through C-H Functionalization has yet be fully explored. Herein, we present successful description photoredox/Cr-catalyzed three-component (hetero)arylalkylation 1,3-dienes functionalization. A diverse array homoallylic alcohols could obtained good excellent yields, accompanied by outstanding enantioselectivity. asymmetric build two simultaneously and demonstrates broad substrate tolerance, accommodating various drug-derived aldehydes, (hetero)aromatics, 1,3-diene derivatives. Preliminary mechanistic studies indicate the involvement radical intermediate, allylic chromium species reacting aliphatic aromatic aldehydes Zimmerman–Traxler transition states enabled dual photoredox catalysis. ongoing Here, authors photoredox- chromium-catalyzed

Язык: Английский

---

Ligand-Controlled, Nickel-Catalyzed Stereodivergent Construction of 1,3-Nonadjacent Stereocenters

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(22), С. 15453 - 15463

Опубликована: Май 25, 2024

In contrast to the asymmetric synthesis of molecules with a single stereocenter or 1,2-adjacent stereocenters, simultaneous construction acyclic 1,3-nonadjacent stereocenters via catalyst in an enantioselective and diastereoselective manner remains formidable challenge. Here, we demonstrate diastereodivergent through Ni-catalyzed reductive cyclization/cross-coupling alkene-tethered aryl bromides α-bromoamides, which represents major remaining stereochemical challenge cyclization/difunctionalization alkenes. Using Ming-Phos as ligand, diverse set oxindoles containing were obtained high levels enantio- diastereoselectivity. Mechanistic experiments density functional theory calculations indicate that magnesium salt plays key role controlling Furthermore, another complementary stereoisomeric products constructed from same starting materials using Ph-Phox ligand.

Язык: Английский

---

Photocatalytic Cyclization Cascades by Radical Relay toward Pyrrolo[1,2-a]indoles: Synthesis, Mechanism, and Application

The Journal of Organic Chemistry, Год журнала: 2024, Номер 89(5), С. 3509 - 3524

Опубликована: Фев. 16, 2024

A photocatalytic annulation cascade of unactivated N-alkene-linked indoles with Langlois' reagent by a radical relay is developed at room temperature under blue LED irradiation. The reaction afforded series tri/difluoromethylated pyrrolo[1,2-a]indoles in moderate to good yields. DFT study suggests that the ascribed rhodamine 6G-induced cyclization involving vinyl addition-radical and hydrogen-atom-abstraction (HAA) processes, interestingly, are applied as fluorescent dyes into fluorescence spectrum live-cell imaging. This paper represents an initial example on cascades HAA process.

Язык: Английский

---

Electroreduction strategy: a sustainable tool for the generation of aryl radicals

Organic Chemistry Frontiers, Год журнала: 2024, Номер 11(15), С. 4318 - 4342

Опубликована: Янв. 1, 2024

This review primarily focuses on the generation of aryl radicals via an electroreduction strategy, and systematically elaborates synthetic applications, scope, limitations substrates.

Язык: Английский

---

Facile Access to Quaternary Carbon Centers via Ni-Catalyzed Arylation of Alkenes with Organoborons

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

Опубликована: Янв. 16, 2025

Quaternary carbon centers are widespread structural motifs, thus representing extensive interest in organic synthesis. We describe here an efficient nickel-catalyzed intermolecular, Markovnikov-selective arylation of minimally functionalized alkenes with stable organoborons, affording a broad range cyclic or acyclic quaternary under mild conditions. The utilization the diimine ligand is critical for high reactivity and chemoselectivity. Furthermore, using bulky chiral as Ni catalyst, stereocenters can be readily prepared levels enantiocontrol. Mechanism studies suggest that, before protonation, rare nickel shift from alkyl to aryl might occur.

Язык: Английский

---

Enantioselective reductive cross-couplings to forge C(sp2)–C(sp3) bonds by merging electrochemistry with nickel catalysis

Nature Communications, Год журнала: 2025, Номер 16(1)

Опубликована: Янв. 28, 2025

Abstract Motivated by the inherent benefits of synergistically combining electrochemical methodologies with nickel catalysis, we present here a Ni-catalyzed enantioselective electroreductive cross-coupling benzyl chlorides aryl halides, yielding chiral 1,1-diaryl compounds good to excellent enantioselectivity. This catalytic reaction can not only be applied chlorides/bromides, which are challenging access other means, but also containing silicon groups. Additionally, absence sacrificial anode lays foundation for scalability. The combination cyclic voltammetry analysis electrode potential studies suggests that Ni I species activate halides via oxidative addition and alkyl single electron transfer.

Язык: Английский

---

Recent Progress in Transition-Metal-Catalyzed Reductive Cross-Coupling Reactions Using Diboron Reagents as Reductants

ACS Catalysis, Год журнала: 2023, Номер 13(23), С. 15469 - 15480

Опубликована: Ноя. 16, 2023

Transition-metal-catalyzed reductive cross-coupling reactions have been developed as one of the important tools for constructing C–C bonds. These involve direct coupling two distinct electrophiles promoted by transition metals and reductants. Notably, these methods offer advantages over conventional because they circumvent need air- moisture-sensitive organometallic reagents while being simple to operate exhibiting good compatibility with various functional groups. In recent years, diboron gained prominence reductants alongside traditional metal reductants, such Zn, Mn, Mg. This Review aims provide an insightful overview nickel/copper/iron-catalyzed using illustrate their possible reaction mechanisms.

Язык: Английский

---