Journal ArticleDOI
Analysis of Substituent Effects on the Claisen Rearrangement with Ab Initio and Density Functional Theory
Reads0
Chats0
TLDR
In this article, the Hartree−Fock method was applied to separate the intrinsic and thermodynamic contributions to the activation energies of 2-and (E)-6-substituted allyl vinyl ethers with CN, CH3 and NH2 groups.Abstract:
Transition structures for the Claisen rearrangements of 2- and (E)-6-substituted allyl vinyl ethers with CN, CH3, and NH2 groups were located with the Hartree−Fock method and the 6-31G* basis set. Energies were obtained using MP2 single points and B3LYP/6-31G* calculations. A Marcus theory type analysis was applied to separate the intrinsic and thermodynamic contributions to the activation energies. The calculations predict a decrease in the activation barrier for the 2-CN, 2-NH2, and 6-NH2 derivatives, while a large increase in the activation energy is predicted for the 6-CN derivative. The 2-CN and 6-NH2 groups decrease the barrier height due to intrinsic contributions, while the rest are controlled by thermodynamic factors. To estimate solvent effects on rates, SCRF calculations for benzene and acetonitrile were performed.read more
Citations
More filters
Journal ArticleDOI
Transition-State Charge Stabilization through Multiple Non-covalent Interactions in the Guanidinium-Catalyzed Enantioselective Claisen Rearrangement
TL;DR: This mechanistic analysis led to the development of a new p-dimethylaminophenyl-substituted catalyst, which afforded improvements in enantioselectivity relative to the parent phenyl catalyst for a representative set of substrates.
Journal ArticleDOI
Catalysis of the Claisen Rearrangement of Aliphatic Allyl Vinyl Ethers
Martin Hiersemann,Lars Abraham +1 more
TL;DR: The thermal Claisen rearrangement of allyl vinyl ethers is generally regarded as high-performance method for diastereoselective C−C bond formation.
Journal ArticleDOI
Practical Organocatalytic Synthesis of Functionalized Non‐C2‐Symmetrical Atropisomeric Biaryls
TL;DR: Density-functional calculations suggest that the quinone and imino-quinone monoacetal coupling partners are exclusively arylated at their α-position by an asynchronous [3,3]-sigmatropic rearrangement of a mixed acetal species which is formed in situ under the reaction conditions.
Journal ArticleDOI
Organocatalytic claisen rearrangement: theory and experiment.
TL;DR: Although the Claisen rearrangement of a 2-alkoxycarbonyl-substituted allyl vinyl ether in the presence of thioureas had a significant transition state stabilization, the overall effect on the barrier is small, in accordance with experimental results.
Journal ArticleDOI
Regioselectivity in aromatic Claisen rearrangements.
Fabio C. Gozzo,Sergio Antonio Fernandes,Denise C. Rodrigues,Marcos N. Eberlin,Anita J. Marsaioli +4 more
TL;DR: B3LYP/6-31G(d,p) calculations on reactants and transition states are shown to correctly predict the outcome of such aromatic Claisen rearrangements from either the preferential reactant ground-state conformation or the less energetic transition state, or both.
References
More filters
Journal ArticleDOI
Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
Journal ArticleDOI
Density-functional exchange-energy approximation with correct asymptotic behavior.
TL;DR: This work reports a gradient-corrected exchange-energy functional, containing only one parameter, that fits the exact Hartree-Fock exchange energies of a wide variety of atomic systems with remarkable accuracy, surpassing the performance of previous functionals containing two parameters or more.
Journal ArticleDOI
On the Theory of Oxidation‐Reduction Reactions Involving Electron Transfer. I
TL;DR: In this paper, a mechanism for electron transfer reactions is described, in which there is very little spatial overlap of the electronic orbitals of the two reacting molecules in the activated complex, and a quantitative theory of the rates of oxidation reduction reactions involving electron transfer in solution is presented.
Journal ArticleDOI
Theoretical relations among rate constants, barriers, and Broensted slopes of chemical reactions
TL;DR: In this paper, a simple relation, ΔF* = (λ(1 + Δ/λ)^2)/4, was explored in a slightly modified version for reactions with considerable resonance splitting, such as atom transfers, proton transfers, and strong-overlap electron transfers.