Control Elements in Dynamically Determined Selectivity on a Bifurcating Surface
| Autor: | Daniel A. Singleton, Jack R. Waas, Jacqueline B. Thomas, Michael Harmata |
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| Rok vydání: | 2008 |
| Předmět: |
Models
Molecular Surface (mathematics) Chemical Phenomena Diene Surface Properties Stereochemistry Kinetics Cyclopentanes Kinetic energy Biochemistry Article Catalysis Bridged Bicyclo Compounds chemistry.chemical_compound Colloid and Surface Chemistry Kinetic isotope effect General Chemistry Ketones Cycloaddition Alkadienes chemistry Cyclization Chemical physics Product (mathematics) Thermodynamics Selectivity |
| Zdroj: | Journal of the American Chemical Society. 130:14544-14555 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja802577v |
| Popis: | The mechanism and the nature of the dynamically determined product selectivity in Diels-Alder cycloadditions of 3-methoxycarbonylcyclopentadienone (2) with 1,3-dienes was studied by a combination of product studies, experimental kinetic isotope effects, standard theoretical calculations, and quasiclassical trajectory calculations. The low-energy transition structures in these reactions are structurally balanced between [4pi(diene) + 2pi(dienone)] and the [2pi(diene) + 4pi(dienone)] modes of cycloaddition. The accuracy of these structures and their bispericyclic nature is supported by the experimental isotope effects. Trajectories passing through these transition structures can lead to both [4pi(diene) + 2pi(dienone)] and [2pi(diene) + 4pi(dienone)] cycloadducts, and the mixture of products obtained varies with the structure of the diene. The factors affecting this selectivity are analyzed. The geometry of the transition structure is a useful predictor of the major product, but the selectivity is also guided by the shape of the energy surface as trajectories approach the products and by how trajectories cross the transition state ridge. |
| Databáze: | OpenAIRE |
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