Kinetic and thermodynamic effects in the thermal electrocyclic ring-openings of 3-fluorocyclobutene, 3,3-difluorocyclobutene, and 3-(trifluoromethyl)cyclobutene

Dolbier, William R.; Gray, Thomas A.; Keaffaber, Jeffrey J.; Celewicz, Lech; Koroniak, Henryk

doi:10.1021/ja00157a055

Cited by 48 publications

(23 citation statements)

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“… Reaction (1): X = CF 3 (56.5–188.5°C); Reaction (2): X = CH 3 , CN (C 6 D 6 /reflux) . The reactions of (a) are competitive with reaction products (b) and (c) formed.…”

Section: Introductionmentioning

confidence: 99%

“…The reactions of (a) are competitive with reaction products (b) and (c) formed. Thermal ring‐opening reactions of 3‐(trifluoromethyl)cyclobut‐1‐ene and 1‐cyano‐1‐methylcyclobutene: undergo thermal ring‐opening reactions to produce the isomers: E‐3‐fluoro‐2,4‐pentadiene, Z‐3‐fluoro‐2,4‐pentadiene and E‐2‐cyano‐2,4‐pentadiene, Z‐2‐cyano‐2,4‐pentadiene, respectively …”

Section: Introductionmentioning

confidence: 99%

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Distinguishing and quantifying the torquoselectivity in competitive ring-opening reactions using the stress tensor and QTAIM

Huan

Morales‐Bayuelo

et al. 2016

J. Comput. Chem.

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Currently the theories to explain and predict the classification of the electronic reorganization due to the torquoselectivity of a ring-opening reaction cannot accommodate the directional character of the reaction pathway; the torquoselectivity is a type of stereoselectivity and therefore is dependent on the pathway. Therefore, in this investigation we introduced new measures from quantum theory of atoms in molecules and the stress tensor to clearly distinguish and quantify the transition states of the inward (TSIC) and outward (TSOC) conrotations of competitive ring-opening reactions of 3-(trifluoromethyl)cyclobut-1-ene and 1-cyano-1-methylcyclobutene. We find the metallicity ξ(r ) of the ring-opening bond does not occur exactly at the transition state in agreement with transition state theory. The vector-based stress tensor response β was used to distinguish the effect of the CN, CH , and CF groups on the TSIC and TSOC paths that was consistent with the ellipticity ε, the total local energy density H(r ) and the stress tensor stiffness S . We determine the directional properties of the TSIC and TSOC ring-opening reactions by constructing a stress tensor UσTS space with trajectories TσTS (s) with length l in real space, longer l correlated with the lowest density functional theory-evaluated total energy barrier and hence will be more thermodynamically favored. © 2016 Wiley Periodicals, Inc.

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“… Reaction (1): X = CF 3 (56.5–188.5°C); Reaction (2): X = CH 3 , CN (C 6 D 6 /reflux) . The reactions of (a) are competitive with reaction products (b) and (c) formed.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Distinguishing and quantifying the torquoselectivity in competitive ring-opening reactions using the stress tensor and QTAIM

Huan

Morales‐Bayuelo

et al. 2016

J. Comput. Chem.

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“…4 The reaction of 3-fluorocyclobutene 3a occurred at lower temperature than that of cyclobutene itself, and the thermodynamically less stable E-diene was selectively formed (Scheme 2). In contrast, 3,3-difluorocyclobutene (3b) and 3-(trifluoromethyl)cyclobutene (3c) were more reluctant to undergo ring opening than cyclobutene.…”

Section: Cyclobutene Ring Openingmentioning

confidence: 99%

5.16 Cyclobutene Ring Opening Reactions

Murakami¹,

Matsuda²

2014

Comprehensive Organic Synthesis II

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“…Trans-3,4-disubstituted cyclobutenes are known to undergo one of the conrotatory isomerizations shown below depending on the identities of R and RЈ, [19][20][21] Letting R and RЈ be methyl groups, we initiated a series of searches from the configuration shown in Fig. 6.…”

Section: B Trans-14-dimethylcyclobutene Rearrangementmentioning

confidence: 99%

“…Experimentally it has been observed that the reaction producing trans-triflouro-pentadiene is about 45 times faster than the reaction resulting in cis-triflouropentadiene. 20,21 Hydrogens in the saddle point geometries from pathways 1 and 2 of the previous study were replaced with flourines to obtain starting geometries for the new transition structures. The fluorinated transition structures were reoptimized at the B3LYP/6-31G* level.…”

Section: ͑15͒mentioning

confidence: 99%

Biasing a transition state search to locate multiple reaction pathways

Peters

Liang

Bell

et al. 2003

The Journal of Chemical Physics

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Articles you may be interested inAb initio reaction pathways for photodissociation and isomerization of nitromethane on four singlet potential energy surfaces with three roaming paths Development and application of a hybrid method involving interpolation and ab initio calculations for the determination of transition states A variety of chemical systems exhibit multiple reaction pathways that adjoin to a common reactant state. In fact, any reaction producing side products or proceeding via a stable intermediate involves a species possessing at least two reaction pathways. Despite improvements in ab initio transition-state search algorithms it remains difficult to detect multiple reaction pathways. Typically, multiple reaction pathways can only be detected by intuitively varying the initial point in the transition-state search trajectory. This reliance on intuition limits the ability to discover new and unexpected chemistry using ab initio methods. This paper proposes a systematic and intuition-free method for biasing a transition-state search to identify multiple reaction pathways originating from a common reactant state. The method allows the successive location of transition states, with each successful search contributing to a cumulative bias potential for the following search. The method is applicable to all psuedo-Newton-Raphson-type transition-state searches. The procedure was tested for a model potential energy surface and for the thermal rearrangement of trans-1,4-dimethylcyclobutene. In the latter case, four reaction pathways were discovered: two exothermic conrotatory ring openings leading to hexadienes, an endothermic methyl migration pathway leading to a carbene, and an exothermic rearrangement leading to 3-methyl-1,4-pentadiene. In accordance with experiment, the calculations predict that the conrotatory pathway leading to trans,trans-2,4-hexadiene is the kinetically dominant pathway. The methodology was also used to compute selectivities for competitive pathways producing trans and cis triflouropentadiene products in the thermal rearrangement of 3-triflouromethyl-cyclobutene. Again, results were in accord with experimental observations.

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Kinetic and thermodynamic effects in the thermal electrocyclic ring-openings of 3-fluorocyclobutene, 3,3-difluorocyclobutene, and 3-(trifluoromethyl)cyclobutene

Cited by 48 publications

References 0 publications

Distinguishing and quantifying the torquoselectivity in competitive ring-opening reactions using the stress tensor and QTAIM

Distinguishing and quantifying the torquoselectivity in competitive ring-opening reactions using the stress tensor and QTAIM

5.16 Cyclobutene Ring Opening Reactions

Biasing a transition state search to locate multiple reaction pathways

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