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How Persistent Is Cyclopropyl upon Nucleophilic Substitution, and Is Frontside Displacement Possible? A Model Study
journal contribution
posted on 2001-09-20, 00:00 authored by Einar UggerudQuantum chemical model calculations (MP2/6-31G(d,p)) demonstrate that frontside nucleophilic
substitution is not possible in the reaction between water and protonated cyclopropanol. Instead,
ring opening occurs, in accordance with a well-known disrotary ring-opening mechanism. When
the cyclopropane ring is embedded in a stabilizing bicyclic structure, as in protonated bicyclo[3.1.0]hexanol, the mechanistic landscape changes. In this case frontside nucleophilic substitution
occurs, and has a potential energy barrier which is lower than that of the corresponding backside
substitution, which implies that the stereochemical outcome of this gas-phase nucleophilic substitution reaction is uncoupled from its kinetic order. This and similar results challenge the traditional
view that nucleophilic substitution reactions should be categorized as being either SN1 or SN2.
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Frontside Displacementprotonated cyclopropanolstereochemical outcomelandscape changesnucleophilic substitution reactionsbicyclic structureNucleophilic Substitutionfrontside nucleophilic substitutionbackside substitutionring openingcyclopropane ringModel Study Quantum chemical model calculationsenergy barrierresults challengeMPS N 1case frontside nucleophilic substitution
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