New Concepts in Organic Selectivity and Mechanisms

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DESCRIPTION (provided by applicant): The conventional framework for understanding reactivity and selectivity in organic reactions fails for reactions influenced by dynamic effects. It is proposed to investigate the role of dynamic effects in some of the most common and important reactions in chemistry. In hydroboration, initially published results have called into question all of the standard ideas used to explain selectivity in these reaction; the proposed studies would use isotope effects and selectivity studies to determine the breadth of importance of dynamic effects in these reactions, and would explore ways to improve selectivity based on the its understanding as a dynamic phenomenon. In [2,3]-sigmatropic rearrangements, initial results suggest that dynamics can provide a unified explanation for competing [2,3] and [1,2] rearrangements, and the proposed mechanistic studies would a broad reinterpretation of these reactions. In Diels-Alder reactions and the [2 + 2] cycloadditions of ketenes, recent studies have found that the Newtonian ideas of inertia and mass-dependent acceleration can be the real deciding factor in selectivity. The proposed studies would examine ways to recognize these effects and how broadly they affect reactions. In ozonolysis, initial results have found that the intermediate primary ozonide is unique "hot" in only part of the molecule, and the planned studies would examine how structural effects on energy motion through molecules affects product ratios. Finally, experimental results have implicated that a dynamic effect, previously considered only for triatomic reactions, broadly facilitates the general acid-base catalyzed reactions of organic and enzymatic chemistry. Experiments are proposed to define in particular examples the role of the effect in catalysis. The health-relatedness of this work derives from its impact on the understanding of reactions important in the synthesis of medicinally important substances and reactions important in biological pathways. PUBLIC HEALTH RELEVANCE: The synthesis of pharmaceuticals and the manipulation of biological pathways depend on the rational design and control of chemical reactions, which in turn depend on the understanding of chemical reactions. Our research is providing fundamental news ways to understand reactions that should aid in their invention, development, and regulation.