scholarly journals Enantiomerically Enriched Tetrahydropyridine Allyl Chlorides

2019 ◽  
Author(s):  
Sedef Karabiyikoglu ◽  
Alexandre Brethomé ◽  
Thomas Palacin ◽  
Robert Paton ◽  
Stephen P. Fletcher
Keyword(s):  
Dft Calculations ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Allyl Chloride ◽  
Reaction Pathways ◽  
Substitution Reactions ◽  
Catalyst Free ◽  
Kinetic Isotope ◽  
Allyl Halides ◽  
Stereoselective Reaction

Enantiomerically enriched allyl halides are rare due to their configurational lability. Here we report stable piperidine-based allyl chloride enantiomers. These allyl chlorides can be produced via resolution, and undergo highly enantiospecific catalyst-free substitution reactions with C, N, O and S-based nucleophiles. Deuterium-labelled chloro-tetrahydropyridine, selectively prepared using the H/D primary kinetic isotope effect, and DFT calculations were used to investigate the mechanisms of the reactions. The allyl chlorides may also serve as valuable mechanistic tools for probing stereoselective reaction pathways.

scholarly journals Enantiomerically Enriched Tetrahydropyridine Allyl Chlorides

2019 ◽  
Author(s):  
Sedef Karabiyikoglu ◽  
Alexandre Brethomé ◽  
Thomas Palacin ◽  
Robert Paton ◽  
Stephen P. Fletcher
Keyword(s):  
Dft Calculations ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Allyl Chloride ◽  
Reaction Pathways ◽  
Substitution Reactions ◽  
Catalyst Free ◽  
Kinetic Isotope ◽  
Allyl Halides ◽  
Stereoselective Reaction

Enantiomerically enriched allyl halides are rare due to their configurational lability. Here we report stable piperidine-based allyl chloride enantiomers. These allyl chlorides can be produced via resolution, and undergo highly enantiospecific catalyst-free substitution reactions with C, N, O and S-based nucleophiles. Deuterium-labelled chloro-tetrahydropyridine, selectively prepared using the H/D primary kinetic isotope effect, and DFT calculations were used to investigate the mechanisms of the reactions. The allyl chlorides may also serve as valuable mechanistic tools for probing stereoselective reaction pathways.

Isotope effects in nucleophilic substitution reactions. VI. The effect of ion pairing on the transition state structure of SN2 reactions

1988 ◽  
Vol 66 (5) ◽  
pp. 1263-1271 ◽  
Author(s):  
Kenneth Charles Westaway ◽  
Zhu-Gen Lai
Keyword(s):  
Transition State ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Isotope Effects ◽  
Ion Pair ◽  
State Structure ◽  
Transition State Structure ◽  
Substitution Reactions ◽  
Sn2 Reactions ◽  
Kinetic Isotope

Spectroscopic and conductivity studies of sodium thiophenoxide solutions in four different solvents and the secondary α-deuterium kinetic isotope effects found in the presence of 15-crown-5 ether demonstrate that the secondary α-deuterium kinetic isotope effect and transition state structure for the SN2 reaction between sodium thiophenoxide and n-butyl chloride are significantly different, depending on whether the ionic reactant is a solvent-separated ion-pair complex or a free ion. In all three solvents in which the form of the ionic reactant changes, a smaller isotope effect and tighter transition state are found for the reaction with the ion-pair complex.

Isotope effects in nucleophilic substitution reactions. II. Secondary α-deuterium kinetic isotope effects: a criterion of mechanism?

1979 ◽  
Vol 57 (9) ◽  
pp. 1089-1097 ◽  
Author(s):  
Kenneth Charles Westaway ◽  
Syed Fasahat Ali
Keyword(s):  
Transition State ◽  
Nucleophilic Substitution ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Substitution Reactions ◽  
Nucleophilic Substitution Reactions ◽  
Kinetic Isotope ◽  
Steric Crowding

A very large secondary α-deuterium kinetic isotope effect of 1.179 ± 0.007 (1.086 ± 0.003 per α-deuterium) has been observed for the SN2 reaction of thiophenoxide ion with benzyldimethylphenylammonium ion in DMF at 0°C. This large isotope effect which is far outside the range reported for SN2 reactions, is attributed to the fact that the extraordinarily large steric crowding around the Cα—H bonds in the substrate is reduced in the SN2 transition state. The structure of the transition state is shown to be consistent with this hypothesis.

scholarly journals [RuII(tpy)(bpy)Cl]+-Catalyzed reduction of carbon dioxide. Mechanistic insights by carbon-13 kinetic isotope effects

2018 ◽  
Vol 54 (61) ◽  
pp. 8518-8521 ◽  
Author(s):  
T. W. Schneider ◽  
M. T. Hren ◽  
M. Z. Ertem ◽  
A. M. Angeles-Boza
Keyword(s):  
Carbon Dioxide ◽  
Dft Calculations ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Ruthenium Complex ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Reduction Reaction ◽  
Kinetic Isotope

13C kinetic isotope effect determinations combined with DFT calculations provide insight on the CO2 reduction reaction catalyzed by a ruthenium complex.

Isotope effect studies on elimination reactions. VI. The mechanism of the bimolecular elimination reaction of 2-arylethylammonium ions

1970 ◽  
Vol 48 (1) ◽  
pp. 125-132 ◽  
Author(s):  
P. J. Smith ◽  
A. N. Bourns
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Isotope Effects ◽  
Nitrogen Isotope ◽  
Reaction Pathways ◽  
Elimination Reaction ◽  
Tracer Studies ◽  
Kinetic Isotope ◽  
Probable Reaction ◽  
Zwitterionic Intermediate

The mechanism of the elimination reaction of 2-arylethyltrimethylammonium ions with ethoxide ion in ethanol has been examined using tracer and kinetic isotope effect techniques. Absence of exchange with solvent of both 2-phenylethyltrimethylammonium-2,2-d2 bromide and 2-(p-trifluoromethylphenyl)-ethyltrimethylammonium-2,2-d2 bromide and the observation of nitrogen isotope effects of 1.3 and 0.9%, respectively, have eliminated a two-step process involving a freely-solvated carbanion intermediate for both salts. The observation of only a slight change in the magnitude of the nitrogen isotope effect when the solvent is changed from ethanol to water has also excluded a zwitterionic intermediate which is specifically hydrogen-bonded to the molecule of ethanol formed by removal of a β-hydrogen by ethoxide ion. Finally, tracer studies using α- and β-dideuterated substrates have eliminated the less probable reaction pathways involving ylide and carbene intermediates. It is concluded that the reaction of 2-arylethyltrimethylammonium salts with ethoxide ion is a concerted E2 process.

Quantum electrocatalysts: theoretical picture, electrochemical kinetic isotope effect analysis, and conjecture to understand microscopic mechanisms

2020 ◽  
Vol 22 (20) ◽  
pp. 11219-11243 ◽  
Author(s):  
Ken Sakaushi
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Effect Analysis ◽  
Kinetic Isotope

The fundamental aspects of quantum electrocatalysts are discussed together with the newly developed electrochemical kinetic isotope effect (EC-KIE) approach.

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