Journal ArticleDOI
Theory of Substituent Effects on Pericyclic Reaction Rates: Alkoxy Substituents in the Claisen Rearrangement
Hi Young Yoo,K. N. Houk +1 more
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In this article, transition structures, activation energies, and reaction energies were calculated by ab initio quantum mechanical methods for the Claisen rearrangements of five hydroxy-substituted allyl vinyl ethers.Abstract:
Transition structures, activation energies, and reaction energies were calculated by ab initio quantum mechanical methods for the Claisen rearrangements of five hydroxy-substituted allyl vinyl ethers. The RHF, DFT(Becke3LYP), and CASSCF methods with the 6-31G* basis set were carried out. There is good agreement with activation energies measured for alkoxy-substituted compounds. The activation energies were separated into thermodynamic and intrinsic effects using Marcus theory as adapted by Murdoch for pericyclic reactions. Intrinsic effects were analyzed by frontier molecular orbital theory. The deuterium kinetic isotope effects calculated at the CASSCF/6-31G* level for the 2-OH allyl vinyl ether are in good agreement with the experimental results for the 2-OSiMe3 derivative, and these calculated isotope effects show much more bond-breaking and less bond-making than those at both the RHF/6-31G* and Becke3LYP/6-31G* levels.read more
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Implicit Solvation Models: Equilibria, Structure, Spectra, and Dynamics.
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PDDG/PM3 and PDDG/MNDO: improved semiempirical methods.
TL;DR: Two new semiempirical methods employing a Pairwise Distance Directed Gaussian modification have been developed, and yield heats of formation for compounds containing C, H, N, and O atoms with significantly improved accuracy over the standard NDDO schemes.
Journal ArticleDOI
N-heterocyclic carbene-catalyzed Ireland-Coates Claisen rearrangement: synthesis of functionalized β-lactones.
Lisa Candish,David W. Lupton +1 more
TL;DR: The N-heterocyclic carbene (NHC)-catalyzed Claisen rearrangement of hybrid Ireland-Coates structures has been achieved, allowing the stereoselective synthesis of highly functionalized β-lactones.
Journal ArticleDOI
Control of kinetics and thermodynamics of [1,5]-shifts by aromaticity: a view through the prism of Marcus theory.
TL;DR: Marcus theory can be applied successfully to other pericyclic shifts such as [1,5]-shifts which involve chlorine and methyl transfer, making these systems interesting models for studying hydrogen tunneling.
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.
References
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