Distinguishing Competing Mechanistic Manifolds for C(acyl)–N Functionalization by a Ni/N-Heterocyclic Carbene Catalyst System DOI Creative Commons
Kaycie R. Malyk,

Vivek G. Pillai,

William W. Brennessel

et al.

Published: June 1, 2023

Carboxylic acid derivatives are appealing alternatives to organohalides as cross-coupling electrophiles for fine chemical synthesis due their prevalence in biomass and bioactive small molecules well ease of preparation handling. Within this family, carboxamides comprise a versatile electrophile class nickel-catalyzed coupling with carbon heteroatom nucleophiles. However, even state-of-the-art C(acyl)–N functionalization reactions typically require high catalyst loadings specific substitution patterns. These challenges have proven difficult overcome, large part limited experimental mechanistic insight. In work, we describe detailed case study acylative catalyzed by the commonly employed Ni/SIPr system (SIPr = 1,3-Bis(2,6-di-isopropylphenyl)-4,5-dihydroimidazol-2-ylidine). Stoichiometric organometallic studies, situ spectroscopic measurements, crossover experiments demonstrate accessibility Ni(0), Ni(I), Ni(II) resting states. Although precatalyst activation limits reaction efficiency, low concentrations active, SIPr-supported Ni(0) select electrophile-first (closed-shell) over competing nucleophile-first (open-shell) manifolds. We anticipate that insights into nature controlling features these distinct pathways likely accelerate rational improvements methodologies involving pervasive carboxamide substrate motifs.

Language: Английский

Enantioselective Cross-[4 + 2]-Cycloaddition/Decarboxylation of 2-Pyrones by Cooperative Catalysis of the Pd(0)/NHC Complex and Chiral Phosphoric Acid DOI
Mengmeng Xu, Pei‐Pei Xie,

Jun‐Xiong He

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(10), P. 6936 - 6946

Published: Feb. 28, 2024

Here, we describe a cooperative Pd(0)/chiral phosphoric acid catalytic system that allows us to realize the first chemo-, regio-, and enantioselective sequential cross-[4 + 2]-cycloaddition/decarboxylation reaction between 2-pyrones unactivated acyclic 1,3-dienes. The key success of this transformation is utilization an achiral N-heterocyclic carbene (NHC) as ligand newly developed chiral cocatalyst. Experimental investigations computational studies support idea Pd(0)/NHC complex acts π-Lewis base increase nucleophilicity 1,3-dienes via η2 coordination, while simultaneously increases electrophilicity by hydrogen bonding. By synergistic catalysis, 2]-cycloaddition decarboxylation proceeds efficiently, enabling preparation wide range vinyl-substituted 1,3-cyclohexadienes in good yields enantioselectivities. synthetic utility demonstrated transformations product various valuable six-membered carbocycles.

Language: Английский

Citations

6
trans-Hydroalkynylation of Internal 1,3-Enynes Enabled by Cooperative Catalysis DOI
Ziyong Wang, Chen Zhang, Jason Wu

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(10), P. 5624 - 5630

Published: March 2, 2023

A cooperative catalyst system involving a Pd(0)/Senphos complex, tris(pentafluorophenyl)borane, copper bromide, and an amine base, is demonstrated to catalyze trans-hydroalkynylation of internal 1,3-enynes. For the first time, Lewis acid shown promote reaction emerging outer-sphere oxidative step. The resulting cross-conjugated dieneynes are versatile synthons for organic synthesis, their characterization reveals distinct photophysical properties depending on positioning donor/acceptor substituents along conjugation path.

Language: Английский

Citations

15
Mechanism of Pd/Senphos-Catalyzed trans-Hydroboration of 1,3-Enynes: Experimental and Computational Evidence in Support of the Unusual Outer-Sphere Oxidative Addition Pathway DOI
Yuanzhe Zhang, Ziyong Wang, Walid Lamine

et al.

The Journal of Organic Chemistry, Journal Year: 2023, Volume and Issue: 88(4), P. 2415 - 2424

Published: Feb. 8, 2023

The reaction mechanism of the Pd/Senphos-catalyzed trans-hydroboration 1,3-enynes was investigated using various experimental techniques, including deuterium and double crossover labeling experiments, X-ray crystallographic characterization model intermediates, progress kinetic analysis. Our data are in support an unusual outer-sphere oxidative addition where catecholborane serves as a suitable electrophile to activate Pd0-bound 1,3-enyne substrate form Pd-η3-π-allyl species, which has been determined be likely resting state catalytic cycle. Double points toward second role played by borane hydride delivery shuttle. Density functional theory calculations reveal that rate-limiting transition is abstraction shuttle, consistent with experimentally rate law: = k[enyne]0[borane]1[catalyst]1. computed activation free energy ΔG‡ 17.7 kcal/mol KIE (kH/kD 1.3) also line observations. Overall, this work establishes Lewis acids such viable electrophilic activators engage underutilized general approach unsaturated substrates.

Language: Английский

Citations

14
A syn outer-sphere oxidative addition: the reaction mechanism in Pd/Senphos-catalyzed carboboration of 1,3-enynes DOI Creative Commons
Ziyong Wang, Walid Lamine, Karinne Miqueu

et al.

Chemical Science, Journal Year: 2023, Volume and Issue: 14(8), P. 2082 - 2090

Published: Jan. 1, 2023

We report a combined experimental and computational study of Pd/Senphos-catalyzed carboboration 1,3-enynes utilizing DFT calculations, 31P NMR study, kinetic Hammett analysis Arrhenius/Eyring analysis. Our mechanistic provides evidence against the conventional inner-sphere β-migratory insertion mechanism. Instead, syn outer-sphere oxidative addition mechanism featuring Pd-π-allyl intermediate followed by coordination-assisted rearrangements is consistent with all observations.

Language: Английский

Citations

12
Pd(0)-Catalyzed Asymmetric Cyclization/Coupling Cascade of Alkyne-Tethered Unsaturated Carbonyls: Development and Mechanism Elucidation DOI
Yi Zhang, Lei Zhu, Song Xue

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(9), P. 5977 - 5986

Published: Feb. 23, 2024

While the Pd(0)-catalyzed cyclization of alkyne-tethered unsaturated carbonyl substrates has been reported, mechanism not well elucidated, and potential asymmetric version remains to be developed. Here, we disclose that a chiral Pd(0) complex can efficiently promote desymmetrizative cyclohexadienones in CH3OH, resultant Pd(II) intermediates further undergo an array tandem coupling reactions, including Suzuki, Sonogashira, even chemoselective reduction by CH3OH absence additional partners. As result, broad spectrum hydrobenzofuran derivatives, having tetra- or trisubstituted exo-alkene motif, is constructed with moderate outstanding enantioselectivity exclusive cis-difunctionalization pattern. In addition, this enantioselective protocol expanded linear carbonyls, new cyclization/coupling cascade bis-alkyne-tethered enones realized efficiently, furnishing diversely structured frameworks high stereoselectivity. Moreover, kinetic transformation for various racemic accomplished under similar catalytic conditions, unusual reactions chemoselectively undertaking Suzuki Sonogashira coupling, occur sequentially, finally yielding two types products, both via either ligand- substrate-based control. The experimental results demonstrate current Pd(0)-based strategy superior classical Pd(II)-catalyzed carbopalladation/cyclization process identical regard synthetic versatility. density functional theory calculations are conducted rationalize oxidative cyclometalation pathway key step, which leads observed cis-difunctionalized products exclusively.

Language: Английский

Citations

4
Palladium-Catalyzed Divergent Synthesis from o-Sulfonamido Trifluoroacetophenones and 2-En-4-ynyl Carbonates DOI

Meng-Qi Gan,

Jian‐Xiang Zhu,

Zhichao Chen

et al.

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 15, 2025

Here we present a palladium-catalyzed divergent transformative reaction between o-sulfonamido trifluoroacetophenones and 2-en-4-ynyl carbonates. A spectrum of enantioenriched 2,5-dihydrofuran-fused tetrahydroquinolines bearing either (Z)- or (E)-exocyclic double bond are constructed with moderate to high enantioselectivity from 5-aryl-substituted carbonates by tuning palladium sources, while analogous 2,3-dihydrofuran-fused products furnished using 5-alkyl-substituted ones.

Language: Английский

Citations

0
Distinguishing Competing Mechanistic Manifolds for C(acyl)–N Functionalization by a Ni/N-Heterocyclic Carbene Catalyst System DOI Creative Commons
Kaycie R. Malyk,

Vivek G. Pillai,

William W. Brennessel

et al.

JACS Au, Journal Year: 2023, Volume and Issue: 3(9), P. 2451 - 2457

Published: Aug. 21, 2023

Carboxylic acid derivatives are appealing alternatives to organohalides as cross-coupling electrophiles for fine chemical synthesis due their prevalence in biomass and bioactive small molecules well ease of preparation handling. Within this family, carboxamides comprise a versatile electrophile class nickel-catalyzed coupling with carbon heteroatom nucleophiles. However, even state-of-the-art C(acyl)–N functionalization reactions typically require high catalyst loadings specific substitution patterns. These challenges have proven difficult overcome, large part limited experimental mechanistic insight. In work, we describe detailed case study acylative catalyzed by the commonly employed Ni/SIPr system (SIPr = 1,3-bis(2,6-di-isopropylphenyl)-4,5-dihydroimidazol-2-ylidine). Stoichiometric organometallic studies, situ spectroscopic measurements, crossover experiments demonstrate accessibility Ni(0), Ni(I), Ni(II) resting states. Although precatalyst activation limits reaction efficiency, low concentrations active, SIPr-supported Ni(0) select electrophile-first (closed-shell) over competing nucleophile-first (open-shell) manifolds. We anticipate that insights into nature controlling features these distinct pathways will accelerate rational improvements methodologies involving pervasive carboxamide substrate motifs.

Language: Английский

Citations

7
Borataalkenes, boraalkenes, and the η2-B,C coordination mode in coordination chemistry and catalysis DOI

Maxwell Eaton,

Yuanzhe Zhang, Shih‐Yuan Liu

et al.

Chemical Society Reviews, Journal Year: 2024, Volume and Issue: 53(4), P. 1915 - 1935

Published: Jan. 1, 2024

This review summarizes the recent advances in synthesis of transition metal borataalkene and boraalkene complexes, η 2 -B,C coordination mode homogeneous catalysis.

Language: Английский

Citations

2
Synthesis of Allenes by Hydroalkylation of 1,3-Enynes with Ketones Enabled by Cooperative Catalysis DOI

Maxwell Eaton,

Yuping Dai,

Ziyong Wang

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(39), P. 21638 - 21645

Published: Sept. 22, 2023

A method for the synthesis of allenes by addition ketones to 1,3-enynes cooperative Pd(0)Senphos/B(C6F5)3/NR3 catalysis is described. wide range aryl- and aliphatic undergo various in high yields at room temperature. Mechanistic investigations revealed a rate-determining outer-sphere proton transfer mechanism, which was corroborated DFT calculations.

Language: Английский

Citations

6
Catalyst-Free α-trans-Selective Hydroboration and (E)-Selective Deuterated Semihydrogenation of Alkynyl Sulfones DOI

Yunnan Duan,

Zhou-Qing Zheng,

Zhiwei Yu

et al.

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 89(12), P. 8326 - 8333

Published: May 31, 2024

Here, we present a straightforward α-trans-selective hydroboration of alkynyl sulfones with NHC–boranes without the need for catalyst. This reaction is compatible wide range substrates efficiently producing structurally diverse α-borylated vinyl in satisfactory yields. The hydride transfer from NHC–borane 2a to triflone 1b studied by density functional theory (DFT) calculations trans-hydroboration. Moreover, regiodivergent deuterated semihydrogenation triflones has also been developed using D2O as deuterium source. A variety diversity-oriented D-containing were prepared good excellent yields incorporation ratios. Synthetic manipulations products are achieved conversion into valuable molecules, indicating utility this protocol.

Language: Английский

Citations

1