Metal‐Free Stereoconvergent C−H Borylation of Enamides DOI Open Access

Tianhang Wang,

Zhengjun Wang,

Minyan Wang

et al.

Angewandte Chemie, Journal Year: 2023, Volume and Issue: 135(44)

Published: Sept. 18, 2023

Abstract Enamides, functional derivatives of enamines, play a significant role as synthetic targets. However, the stereoselective synthesis these molecules has posed longstanding challenge in organic chemistry, particularly for acyclic enamides that are less thermodynamically stable. In this study, we present general strategy constructing β‐borylenamides by C−H borylation, which provides versatile platform generating stereodefined enamides. Our approach involves utilization metalloid borenium cation, generated through reaction BBr 3 and presence two different additives, avoiding any exogenous catalyst. Importantly, stereoconvergent nature methodology allows use starting materials with mixed E/Z configurations, thus highlighting unique advantage chemistry. Mechanistic investigations have shed light on pivotal roles played reactive boron species, phenomenon stereoconvergence.

Language: Английский

Selective Monoborylation of Methane by Metal-Organic Framework Confined Mononuclear Pyridylimine-Iridium(I) Hydride DOI

Rahul Kalita,

Manav Chauhan,

Poorvi Gupta

et al.

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(51), P. 6504 - 6507

Published: Jan. 1, 2024

Chemoselective monoborylation of methane in high yield is a grand challenge. We have developed metal-organic framework confined pyridylimine-iridium hydride catalyst, which efficient C-H borylation using bis(pinacolato)diboron to afford methyl boronic acid pinacol ester 98% GC-yield at 130 °C with TON 196. Mechanistic investigation suggests the oxidative addition Ir

Language: Английский

Citations

9
An Operationally Unsaturated Iridium-Pincer Complex That C–H Activates Methane and Ethane in the Crystalline Solid-State DOI Creative Commons
Matthew R. Gyton, M. Arif Sajjad,

Daniel J. Storm

et al.

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 25, 2025

The known complex [Ir(tBu-PONOP)MeH][BArF4], 1[BArF4] [tBu-PONOP = κ3-2,6-(tBu2PO)2C5H3N); ArF 3,5-(CF3)2(C6H3); J. Am. Chem. Soc. 2009, 131, 8603], is a robust precursor for in crystallo single-crystal to (SC-SC) C–H activation of methane and ethane at 80 °C. This contrasts with the reported solution (CD2Cl2) behavior, where decomposes by loss. Crystalline accessed as single polymorph on gram scale. A neutron diffraction study locates hydride. 13C{1H} SSNMR experiments 1[BArF4], its isotopologue [Ir(tBu-PONOP)(CD3)D][BArF4], d4-1[BArF4], suggest rapid reversible endergonic reductive bond formation occurring access an Ir(I) σ-methane complex. Heating °C under high vacuum results loss intramolecular form cyclometalated [Ir(cyclo-tBu-PONOP′)H][BArF4], 2[BArF4], SC-SC reaction. reversible, addition CH4 or CD4 2[BArF4] equilibrium respectively. Complex thus operationally unsaturated source 14-electron [Ir(tBu-PONOP)][BArF4], III, that undergoes methane. Periodic DFT studies, alongside isotope labeling experiments, link 2[BArF4]/CH4 via elimination/oxidative pathway. N2 forms [Ir(tBu-PONOP)(κ1-N2)][BArF4], transformation. Reaction CO [Ir(tBu-PONOP)(CO)][BArF4] room temperature. Calculations reaction occurs associative process competitively through while only operates. atmosphere alkane dehydrogenation, SC–SC reaction, forming ∼1:1 mixture [Ir(tBu-PONOP)(η2-H2C═CH2)][BArF4], [Ir(tBu-PONOP)H2][BArF4].

Language: Английский

Citations

1
Bridging Homogeneous and Heterogeneous Catalysis: Phosphine‐Functionalized Metal‐Organic Frameworks DOI Creative Commons
Wenmiao Chen, Peiyu Cai, Hong‐Cai Zhou

et al.

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 63(12)

Published: Dec. 23, 2023

Abstract Phosphine‐functionalized metal‐organic frameworks (P‐MOFs) as an emerging class of coordination polymers, have provided novel opportunities for the development heterogeneous catalysts. Yet, compared with ubiquitous phosphine systems in homogeneous catalysis, heterogenization phosphines MOFs is still at its early stage. In this Minireview, we summarize synthetic strategies, characterization and catalytic reactions based on P‐MOFs reported literature. particular, various are discussed detail terms ligand structure‐function relationship, including potential obstacles future development. Finally, discuss possible solutions, new types techniques perspectives P‐MOF catalysts, highlighting challenges.

Language: Английский

Citations

16
Metal‐Free Stereoconvergent C−H Borylation of Enamides DOI

Tianhang Wang,

Zhengjun Wang,

Minyan Wang

et al.

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(44)

Published: Sept. 18, 2023

Enamides, functional derivatives of enamines, play a significant role as synthetic targets. However, the stereoselective synthesis these molecules has posed longstanding challenge in organic chemistry, particularly for acyclic enamides that are less thermodynamically stable. In this study, we present general strategy constructing β-borylenamides by C-H borylation, which provides versatile platform generating stereodefined enamides. Our approach involves utilization metalloid borenium cation, generated through reaction BBr3 and presence two different additives, avoiding any exogenous catalyst. Importantly, stereoconvergent nature methodology allows use starting materials with mixed E/Z configurations, thus highlighting unique advantage chemistry. Mechanistic investigations have shed light on pivotal roles played reactive boron species, phenomenon stereoconvergence.

Language: Английский

Citations

14
Alkene Isomerization Using a Heterogeneous Nickel-Hydride Catalyst DOI

Alison Sy-min Chang,

Melanie A. Kascoutas,

Quinn Valentine

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(22), P. 15596 - 15608

Published: May 21, 2024

Transition metal-catalyzed alkene isomerization is an enabling technology used to install distal its original site. Due their well-defined structure, homogeneous catalysts can be fine-tuned optimize reactivity, stereoselectivity, and positional selectivity, but they often suffer from instability nonrecyclability. Heterogeneous are generally highly robust continue lack active-site specificity challenging rationally improve through structural modification. Known single-site heterogeneous for utilize precious metals bespoke, expensive, synthetically intense supports. Additionally, have mediocre inspiring us develop a catalyst with active site made readily available compounds of Earth-abundant elements. Previous work demonstrated that very formed upon protonation Ni[P(OEt)3]4 by H2SO4, generating [Ni–H]+ This incredibly active, also decomposes readily, which severely limits utility. Herein we show using solid acid (sulfated zirconia, SZO300), not only this decomposition prevented, high activity maintained, improved selectivity achieved, broader scope functional groups tolerated. Preliminary mechanistic experiments suggest the catalytic reaction likely goes intermolecular, two-electron pathway. A detailed kinetic study comparing state-of-the-art Ni Pd reveals highest seen Ni/SZO300 system. The reactivity Ni/SZO300, limited isomerization; it competent hydroalkenylation, hydroboration, hydrosilylation, demonstrating broad application catalyst.

Language: Английский

Citations

5
Enhanced Activity from Coordinatively Unsaturated and Dynamic Zeolite-Bound Organoscandium Species DOI
Scott A. Southern, Yuting Li, Da‐Jiang Liu

et al.

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(12), P. 9440 - 9451

Published: June 7, 2024

Scandium borohydride grafted into the micropores of faujasite zeolite HY30 catalyzes C–H borylation benzene, whereas silica-grafted species are inactive. This catalytic activity may originate from grafting at a Brønsted acid site leading to more electron-deficient rare earth center. Herein, we apply multinuclear double-resonance nuclear magnetic resonance (NMR) experiments probe structure and dynamics zeolite- silica-bound scandium complexes. The reveal that centers located within micropores, in proximity Al-created sites, dynamic than rigid sites on silanols. Through combination NMR molecular simulations, show coordination is labile, with metal exchanging between two binding sites. weak electron donation support enables movement Sc center leads formation an undercoordinated cannot exist silica, ultimately new species.

Language: Английский

Citations

4
MOF-Supported Diphosphine Ligands for Iridium-Catalyzed C–H Borylation of Arenes DOI

Jordon S. Hilliard,

Daniel J. Murray, Ankita Saha

et al.

Inorganic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: April 1, 2025

Postsynthetic methods have been used to immobilize a carboxylate-functionalized diphosphine ligand, N,N-bis[(diphenylphosphino)methyl]glycinate (dppmg), in different metal-organic framework (MOF) supports. H(dppmg) reacts quantitatively with Zn-OH groups MFU-4l-OH (1) provide solid-state ligands (1-H-x) controllable loadings. metalation [Ir(OMe)(cod)]2 (cod = 1,5-cyclooctadiene) generates heterogeneous precatalysts (1-Ir-x) that show excellent activity toward C-H borylation of arenes. This is dependent on both the catalyst site density and initial concentration borylating reagent. Homogeneous catalysts supported by analogous exhibit low catalytic activity, demonstrating beneficial role isolation. Immobilization dppmg-Ir at Zr-based nodes MOF-808 (2-P-Ir) NU-1000 (3-P-Ir) results materials relatively poor toluene, revealing importance MOF support design.

Language: Английский

Citations

0
Group 10 Metal Allyl Amidinates: A Family of Readily Accessible and Stable Molecular Precursors to Generate Supported Nanoparticles DOI Creative Commons
Christian Ehinger, X. K. Zhou,

Max Candrian

et al.

JACS Au, Journal Year: 2023, Volume and Issue: 3(8), P. 2314 - 2322

Published: Aug. 1, 2023

The synthesis of well-defined materials as model systems for catalysis and related fields is an important pillar in the understanding catalytic processes at a molecular level. Various approaches employing organometallic precursors have been developed established to make monodispersed supported nanoparticles, nanocrystals, films. Using rational design principles, new family based on group 10 metals suitable generation small nanoparticles metal oxides has developed. Particle formation SiO2 Al2O3 supports demonstrated, well potential bimetallic catalyst materials, exemplified by PdGa/SiO2 system capable hydrogenation CO2 methanol. In addition surface chemistry (SOMC), it envisioned that these could also be employed applications, such atomic layer deposition, due their inherent volatility relative thermal stability.

Language: Английский

Citations

10
Catalyst Design for Rh-Catalyzed Arene and Alkane C–H Borylation: The NHC Affects the Induction Period, and Indenyl is Superior to Cp DOI Creative Commons
Paul A. Morton,

Abigayle L. Boyce,

Anamarija Pišpek

et al.

Organometallics, Journal Year: 2024, Volume and Issue: 43(9), P. 974 - 986

Published: March 28, 2024

In order to establish design criteria for Rh C–H borylation catalysts, analogues of the successful catalyst [Rh(Ind)(SIDipp)(COE)] (Ind = η5-indenyl, SIDipp 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene, and COE cis-cyclooctene) were synthesized by changing indenyl carbene ligands. [RhCp(SIDipp)(COE)] (1) formed alongside C–C activated, cyclometalated byproduct [RhCp(κ2CAr,Ccarbene-SIDipp′)(iPr)] (rac-2; SIDipp′ 1-(6-isopropylphenyl)-3-(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene). Computational modeling dissociation showed that both activation aryl group is thermally attainable reversible under experimental conditions, with products being more thermodynamically stable species. Oxidative addition 1 SiH(OEt)3 gave silyl hydride [RhCp(H){Si(OEt)3}(SIDipp)] (rac-3). [Rh(Ind)(IDipp)(COE)] (4; IDipp 1,3-bis(2,6-diisopropylphenyl)-imidazole-2-ylidene), carbonyl analogue [Rh(Ind)(IDipp)(CO)] (5; νCO 1940 cm–1, cf. 1944 cm–1 [Rh(Ind)(SIDipp)(COE)]), [Rh(Ind)(IMe4)(COE)] (6; IMe4 1,3,4,5-tetramethylimidazol-2-ylidene) also characterized, but attempts synthesize complexes fluorenyl or 1,2,3,4-tetrahydrofluorenyl ligands not successful. For catalytic benzene using B2pin2, was inactive at 80 °C, superior all other tested due shortest induction period. However, HBpin precatalyst 4 eliminated Catalytic n-alkane [Rh(Ind)(NHC)(COE)] yields up 21% alkylBpin, [RhCp*(C2H4)2] better catalyst.

Language: Английский

Citations

2
Bridging Homogeneous and Heterogeneous Catalysis: Phosphine‐Functionalized Metal‐Organic Frameworks DOI Creative Commons
Wenmiao Chen, Peiyu Cai, Hong‐Cai Zhou

et al.

Angewandte Chemie, Journal Year: 2023, Volume and Issue: 136(12)

Published: Dec. 23, 2023

Abstract Phosphine‐functionalized metal‐organic frameworks (P‐MOFs) as an emerging class of coordination polymers, have provided novel opportunities for the development heterogeneous catalysts. Yet, compared with ubiquitous phosphine systems in homogeneous catalysis, heterogenization phosphines MOFs is still at its early stage. In this Minireview, we summarize synthetic strategies, characterization and catalytic reactions based on P‐MOFs reported literature. particular, various are discussed detail terms ligand structure‐function relationship, including potential obstacles future development. Finally, discuss possible solutions, new types techniques perspectives P‐MOF catalysts, highlighting challenges.

Language: Английский

Citations

6