Stereomutation of cyclopropane revisited. An ab initio investigation of the potential surface and calculation of secondary isotope effects

Getty, Stephen J.; Davidson, Ernest R.; Borden, Weston Thatcher

doi:10.1021/ja00032a023

Cited by 72 publications

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“…This k α value (k α = (4k 1 + 4k 12 )) and the rate constant for geometrical isomerizations of the 13 C, d 3 -labeled cyclopropanes determined by tunable diode laser spectroscopy (5, 11) (k i = (8k 1 + 4k 12 ) = (4.63 ± 0.20) × 10 -5 s -1 ) provided values of k 1 = (0.38 ± 0.05) × 10 -5 s -1 and k 12 = (0.39 ± 0.05) × 10 -5 s -1 , thus demonstrating that the thermal stereomutations of isotopically labeled cyclopropanes occur as both one-center and two-center epimerizations and take place with comparable rate constants. This experimental result is now reflected in theoretical calculations and models from several laboratories (12)(13)(14)(15)(16)(17)(18)(19).…”

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confidence: 74%

“…Mots clés : stéréomutations du cyclopropane, épimérisations thermiques, chiralité due au marquage au deutérium et au 13 C, dichroïsme circulaire vibrationnel.…”

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“…The present report presents in full detail the VCD spectroscopic data from which a k α value for (2S,3S)-1 may be derived. While the method and instrumentation used have been detailed in print (4), and the VCD spectra have been available in a dissertation since 1991 (20), this account, prompted by colleagues and a recent renewal of interest in the cyclopropane stereomutation problem (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23), offers a complete presentation of spectral data and an alternative, independent procedure for data reduction. It provides, in a still more readily accessible form, information necessary for judging the power of VCD spectroscopy applied to problems of this sort.…”

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confidence: 99%

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Kinetics of thermal racemization of (2S,3S)-1-¹³C-1,2,3-d₃-cyclopropane followed by vibrational circular dichroism spectroscopy

Freedman¹,

Hausch²,

Cianciosi³

et al. 1998

Can. J. Chem.

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Vibrational circular dichoism spectra recorded for (2S,3S)-1-13 C-1,2,3-d 3 -cyclopropane and for mixtures of it and the three related stereoisomers prepared through gas-phase thermal stereomutation reactions at 407°C lead to the rate constant for racemization: k α = (4k 1 + 4k 12 ) = (3.12 ± 0.04) × 10 -5 s -1 . This and the rate constant measured for geometrical equilibration between the two chiral and the two achiral stereoisomers of 1-13 C-1,2,3-d 3 -cyclopropane, k i = (8k 1 + 4k 12 ) = (4.63 ± 0.20) × 10 -5 s -1 , give two equations in two unknowns, and allow one to solve for one-center (k 1 ) and two-center (k 12 ) epimerization rate constants for cyclopropane stereomutations. They are nearly equal, a clear indication of closely competitive reaction pathways.

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confidence: 74%

“…Mots clés : stéréomutations du cyclopropane, épimérisations thermiques, chiralité due au marquage au deutérium et au 13 C, dichroïsme circulaire vibrationnel.…”

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confidence: 99%

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Kinetics of thermal racemization of (2S,3S)-1-¹³C-1,2,3-d₃-cyclopropane followed by vibrational circular dichroism spectroscopy

Freedman¹,

Hausch²,

Cianciosi³

et al. 1998

Can. J. Chem.

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“…[20,21] Since this value is for the process that leads to [D 6 ]propene, and involves a rate-determining 1,2 H(D)-shift, this is clearly a primary isotope effect, although augmented by secondary effects. For the more specific ringopening process of 1,2-dideuteriocyclopropane, not involving H(D)-transfer, calculations give values in the region of 1.13 ± 1.18 at 696 K [22,23] for the specific secondary isotope effect per deuterium atom. Thus the value for the isotope effect found here, based on these analogues, looks to be too large to be secondary.…”

Section: In Memory Of Wolfgang Rothmentioning

confidence: 97%

Alkyl Migration Aptitudes in the Vinylidene–Acetylene Rearrangement and Isotope Effect in the Vinylidene Formation Process from a Deuterium-Labeled Cyclopropene

Schulenburg

Hopf

Walsh

1999

Angew. Chem. Int. Ed.

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The secret of the mechanism of vinylidene rearrangements has been unlocked by the use of specifically labeled cyclopropenes under mild thermal conditions (see the Equations). (13) C labeling gives the surprising 1,2-alkyl migratory aptitude sequence Et>iPr>Me. Deuterium labeling yields the first measurement of the primary kinetic isotope effect in the ring opening of a cyclopropene to form a vinylidene.

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“…144 In contrast, John assumed that the mode by which a molecule undergoes ringopening will have no effect on the mode by which it undergoes ring closure. 145 Since ring-opening by one mode of coupled rotation (e.g., conrotation), followed by ring closure by the opposite mode (e.g., disrotation) has the net effect of a single rotation, John's analysis predicted much more single rotation than our analysis did.…”

Section: Abmentioning

confidence: 99%

With a Little Help from My Friends: Forty Years of Fruitful Chemical Collaborations

Borden

2011

J. Org. Chem.

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A former colleague of mine at the University of Washington once told me, only half-jokingly, "You do a lot of collaborative research, and I think the reason for its success is that you are brave enough to choose as your collaborators people who are better chemists than you." Looking back over the past 40 years of my career, I have, indeed, had an unusually large number of research collaborations, and they have, in fact, been successful, largely because my collaborators have all been talented chemists who had expertise that I lacked.These collaborations have come about in several ways. In some cases, an experimentalist has asked my research group to perform calculations. On other occasions, I have sought collaborators outside of my own research group when I needed help, usually experimental but sometimes computational, in testing a prediction. I have also had research collaborations begin when I was on sabbatical or when Professors from other universities spent sabbaticals in my research group, usually with the goal of learning how to do electronic structure calculations.This Perspective allows me to thank at least a few of my many collaborators over the past 40 years by recounting how their contributions made it possible for me to do research that I probably would not have been able to do on my own. This Perspective also gives me the opportunity to give some examples of the synergism between theory and experiments in my research and to acknowledge the important role that serendipity has played throughout my career, but particularly in the collaborative projects that are the focus of this Perspective. I have been lucky in having had puzzling experimental and computational results brought to my attention at times when I had the knowledge and/or computational resources that were necessary in order to explain those results. I have also been very fortunate in knowing experimentalists and theoreticians who were willing to collaborate with me on experiments and calculations that were of interest to me, but which I could not have readily done on my own.Serendipity has also played a different kind of role in my research. When I have been working on finding the solution to a specific problem, my research has frequently led me to the solution of a problem of much broader scope. I attribute my good fortune, at least in part, to my compulsive habit of persistently asking myself the question, "Why is that?" when I am presented with an experimental or computational result that I do not understand.I have divided this Perspective into eight major sections, each of which describes a different area of my research during the past 40 years, in which collaborations have played an important role. Rather than reading this Perspective in its entirety, some readers may prefer to be selective and peruse just a few of the eight sections. The sections cover my collaborative research on (1) hydrocarbons containing unsaturatively 1,3-bridged cyclobutane rings, (2) the use of orbital topology for predicting the ground states of diradicals, (3)...

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Stereomutation of cyclopropane revisited. An ab initio investigation of the potential surface and calculation of secondary isotope effects

Cited by 72 publications

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Kinetics of thermal racemization of (2S,3S)-1-¹³C-1,2,3-d₃-cyclopropane followed by vibrational circular dichroism spectroscopy

Kinetics of thermal racemization of (2S,3S)-1-¹³C-1,2,3-d₃-cyclopropane followed by vibrational circular dichroism spectroscopy

Alkyl Migration Aptitudes in the Vinylidene–Acetylene Rearrangement and Isotope Effect in the Vinylidene Formation Process from a Deuterium-Labeled Cyclopropene

With a Little Help from My Friends: Forty Years of Fruitful Chemical Collaborations

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Stereomutation of cyclopropane revisited. An ab initio investigation of the potential surface and calculation of secondary isotope effects

Cited by 72 publications

References 0 publications

Kinetics of thermal racemization of (2S,3S)-1-13C-1,2,3-d3-cyclopropane followed by vibrational circular dichroism spectroscopy

Kinetics of thermal racemization of (2S,3S)-1-13C-1,2,3-d3-cyclopropane followed by vibrational circular dichroism spectroscopy

Alkyl Migration Aptitudes in the Vinylidene–Acetylene Rearrangement and Isotope Effect in the Vinylidene Formation Process from a Deuterium-Labeled Cyclopropene

With a Little Help from My Friends: Forty Years of Fruitful Chemical Collaborations

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Kinetics of thermal racemization of (2S,3S)-1-¹³C-1,2,3-d₃-cyclopropane followed by vibrational circular dichroism spectroscopy

Kinetics of thermal racemization of (2S,3S)-1-¹³C-1,2,3-d₃-cyclopropane followed by vibrational circular dichroism spectroscopy