Alder-ene reaction: aromaticity and activation-strain analysis.
Israel Fernández1, F Matthias Bickelhaupt
1Departamento de Química Orgánica, Facultad de Química, Universidad Complutense, Madrid 28040, Spain. israel@quim.ucm.es
This study computationally explores Alder-ene reaction trends. Reactivity barriers decrease when third-period atoms like sulfur or phosphorus are in the enophile, impacting reaction pathways.
Area of Science:
- Computational Chemistry
- Organic Reaction Mechanisms
Background:
- The Alder-ene reaction is a fundamental organic transformation.
- Understanding factors influencing its reactivity is crucial for synthetic chemistry.
Purpose of the Study:
- To computationally investigate the reactivity trends of Alder-ene reactions.
- To elucidate the relationship between enophile structure and reaction barriers.
Main Methods:
- Density Functional Theory (DFT) calculations were employed.
- The M06-2X/def2-TZVPP level of theory was utilized.
- Activation-strain analyses were performed.
Main Results:
- A clear trend in reactivity was observed across seven different enophiles.
- Reaction barriers decreased significantly when third-period atoms (P, S) were part of the enophile's double bond.
- Reactivity correlated with the activation strain of the reactants.
Conclusions:
- The electronic and steric properties of the enophile, particularly the presence of heavier atoms, significantly influence Alder-ene reaction rates.
- Activation strain provides a valuable metric for predicting reactivity trends in these reactions.
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