DFT Investigation of the Palladium‐Catalyzed Ene–Yne Coupling

Henriksen, Signe Teuber; Tanner, David; Skrydstrup, Troels; Norrby, Per‐Ola

doi:10.1002/chem.201001158

Cited by 15 publications

(11 citation statements)

References 47 publications

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“…The LanL2DZ effective core potential basis set was employed for Cu atom while the 6-31+G(d,p) basis set was assigned to nonmetal atoms (C, H, O, N and Br). [15] Vibrational frequencies were calculated for the optimized geometries to characterize the stationary points as real minima or saddle points on the respective potential energy hypersurfaces. [16] Transition states were optimized using the default Berny algorithm implemented in Gaussian 09 and further analyzed by intrinsic reaction coordinate (IRC) computations to confirm that they connect the right reactants and products.…”

Section: Computational Methodologymentioning

confidence: 99%

A Theoretical Insight into the Mechanism of Cu(I)‐Catalyzed CN Coupling between Aryl Halides and Aqueous Ammonia

et al. 2015

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Computational investigations of Cu(I)-catalyzed C-N coupling between aryl halides and aqueous ammonia without addition of any base or ligand were reported. Density functional theory calculations were performed to reveal the mechanism of the ligand-free amination reaction for the preparation of primary aromatic amines. Through systematic evaluation of the relative concentrations of possible Cu species in solution, we propose that the active catalyst is the neutral Cu(I) complexes rather than the Cu(I) cations; oxidative addition of aryl bromide is a facile step of the catalytic cycle; reactant (NH 3 ) and solvent molecule (NMP) can act as ligands of Cu species to help reduce the activation energy of the forward reaction and increase the activation energy of the reverse reaction; except for Pathway B, the deprotonation step is irreversible due to the extreme exothermic feature; the elimination of H 2 O is kinetically favored, while that of HBr is thermodynamically preferred. These findings should be valuable for the mechanism understandings of the ligand-free Cu-catalyzed C-N cross-coupling reactions and for the further development of highly efficient amination catalyst systems.

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Section: Computational Methodologymentioning

confidence: 99%

A Theoretical Insight into the Mechanism of Cu(I)‐Catalyzed CN Coupling between Aryl Halides and Aqueous Ammonia

et al. 2015

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“…The two corresponding transition states model a rotation of the H–Pd–I fragment to place the H–Pd bond parallel to the CC bond . The computed activation energy for the insertion leading to intermediate II is slightly lower than that required to form intermediate V (Δ E ⧧ = 2.4 kcal mol –1 vs 3.1 kcal mol –1 ).…”

Section: Mechanistic and Computational Studiesmentioning

confidence: 97%

Palladium-Catalyzed Hydrohalogenation of 1,6-Enynes: Hydrogen Halide Salts and Alkyl Halides as Convenient HX Surrogates

Petrone

Franzoni

et al. 2017

J. Am. Chem. Soc.

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Difficulties associated with handling H and CO in metal-catalyzed processes have led to the development of chemical surrogates to these species. Despite many successful examples using this strategy, the application of convenient hydrogen halide (HX) surrogates in catalysis has lagged behind considerably. We now report the use of ammonium halides as HX surrogates to accomplish a Pd-catalyzed hydrohalogenation of enynes. These safe and practical salts avoid many drawbacks associated with traditional HX sources including toxicity and corrosiveness. Experimental and computational studies support a reaction mechanism involving a crucial E-to-Z vinyl-Pd isomerization and a carbon-halogen bond-forming reductive elimination. Furthermore, rare examples of C(sp)-Br and -Cl reductive elimination from Pd(II) as well as transfer hydroiodination using 1-iodobutane as an alternate HI surrogate are also presented.

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“…22,23,32–41 Many studies have focused on the main selectivity-determining step, the migratory insertion. 19,20,42–44 In addition, the β -hydride elimination step that is an important feature of the current reaction has also been investigated. 30,31 For asymmetric Heck reactions, previous studies have focused on cyclic sub- strates.…”

Section: Introductionmentioning

confidence: 99%

Mechanism, Reactivity, and Selectivity in Palladium-Catalyzed Redox-Relay Heck Arylations of Alkenyl Alcohols

et al. 2014

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The enantioselective Pd-catalyzed redox-relay Heck arylation of acyclic alkenyl alcohols allows access to various useful chiral building blocks from simple olefinic substrates. Mechanistically, after the initial migratory insertion, a succession of β-hydride elimination and migratory insertion steps yields a saturated carbonyl product instead of the more general Heck product, an unsaturated alcohol. Here, we investigate the reaction mechanism, including the relay function, yielding the final carbonyl group transformation. M06 calculations predict a ΔΔG‡ of 1 kcal/mol for the site selectivity and 2.5 kcal/mol for the enantioselectivity, in quantitative agreement with experimental results. The site selectivity is controlled by a remote electronic effect, where the developing polarization of the alkene in the migratory insertion transition state is stabilized by the C–O dipole of the alcohol moiety. The enantioselectivity is controlled by steric repulsion between the oxazoline substituent and the alcohol-bearing alkene substituent. The relay effeciency is due to an unusually smooth potential energy surface without high barriers, where the hydroxyalkyl-palladium species acts as a thermodynamic sink, driving the reaction toward the carbonyl product. Computational predictions of the relative reactivity and selectivity of the double bond isomers are validated experimentally.

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DFT Investigation of the Palladium‐Catalyzed Ene–Yne Coupling

Cited by 15 publications

References 47 publications

A Theoretical Insight into the Mechanism of Cu(I)‐Catalyzed CN Coupling between Aryl Halides and Aqueous Ammonia

A Theoretical Insight into the Mechanism of Cu(I)‐Catalyzed CN Coupling between Aryl Halides and Aqueous Ammonia

Palladium-Catalyzed Hydrohalogenation of 1,6-Enynes: Hydrogen Halide Salts and Alkyl Halides as Convenient HX Surrogates

Mechanism, Reactivity, and Selectivity in Palladium-Catalyzed Redox-Relay Heck Arylations of Alkenyl Alcohols

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