Dynamic Origin of the Stereoselectivity of a Nucleophilic Substitution Reaction

Bogle, Xavier; Singleton, Daniel A.

doi:10.1021/ol300817a

Cited by 63 publications

(51 citation statements)

References 37 publications

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“…From DBB*, there is no direct 1,2-aryl shift pathway via a concerted transition state (single first-order saddle-point connecting DBB* and BR-I). [27][28][29] In summary, the DPM rearrangement of dibenzobarrelene proceeds via a triplet state, with decay to the ground state via ISC only after BR-II is formed. This flat region can lead to trajectories traversing a pathway represented by the dashed arrow.…”

Section: Angewandte Chemiementioning

confidence: 97%

“…[21][22][23][24][25][26] Singleton has uncovered several such examples for typical organic reactions. [27][28][29] In summary, the DPM rearrangement of dibenzobarrelene proceeds via a triplet state, with decay to the ground state via ISC only after BR-II is formed. The minimum energy reaction pathway involves two barriers on the corresponding triplet state.…”

Section: Angewandte Chemiementioning

confidence: 97%

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The Triplet Surface of the Zimmerman Di‐π‐Methane Rearrangement of Dibenzobarrelene

Matute

Houk

2012

Angew Chem Int Ed

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High-level calculations: the Zimmerman di-π-methane rearrangement of dibenzobarrelene occurs via a triplet state to form dibenzosemibullvalene, overcoming two barriers connecting two biradicals. The shape of the triplet potential-energy surface shows that the rearrangement involves two transition states. The first triplet diradical intermediate may bypass in the passive of the alkene triplet to the final intermediate.

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Section: Angewandte Chemiementioning

confidence: 97%

Section: Angewandte Chemiementioning

confidence: 97%

The Triplet Surface of the Zimmerman Di‐π‐Methane Rearrangement of Dibenzobarrelene

Matute

Houk

2012

Angew Chem Int Ed

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“…It may not just be a matching of momentum between an entrance and an exit channel on a surface, as discussed in Section 8.3.2, that are important but also matching up vibrational motion(s) that lead to specific products. 96,97 The importance of dynamics cannot be overstated for reactions on bifurcating surfaces and clearly additional research needs to be done, especially to aid in creating more robust predictive models. 91 A broad array of organic reactions displays bifurcating PESs.…”

Section: Mementioning

confidence: 99%

Organic Reaction Dynamics

Bachrach

2014

Computational Organic Chemistry

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In the previous chapters, we have focused our discussion of reaction mechanisms on the critical points along the reaction path. These critical points-local energy minima (reactants, intermediates, and products) and transition states (TSs)-were discussed in terms of their geometries and energies. We discussed the nature of the mechanism in terms of the topology of the potential energy surface (PES), the structure of the TSs, and the presence or absence of intermediates. We think of reactants progressing over TSs on to intermediates, perhaps through multiple intermediates and ending at products. This path is called the reaction coordinate and corresponds to the intrinsic reaction coordinate (IRC) or the minimum energy path (MEP) (see Section 1.6 for discussion on these two paths).This standard mechanistic analysis has a long successful history. Organic chemistry textbooks are filled with PESs and discussions of the implication of single-step versus multiple-step mechanisms, concerted TSs, and so on. 1,2 Transition state theory (TST) and Rice-Ramsperger-Kassel-Marcus (RRKM) theory provide tools for predicting rates based upon simple assumptions built upon the notion of reaction on the PES following the reaction coordinate. 3,4 An often-overlooked aspect of standard reaction mechanistic thought is that it really addresses only half of the picture. We talk about the positions of the atoms during the course of the reaction and the relative energies of points along the reaction path, but no mention is made of the time evolution of this process. In classical mechanics, description of a reactive system requires not just the particle positions but their momenta as well. The same is true for a quantum mechanical description, though one must keep in mind the limits imposed by the Heisenberg Uncertainty Principle. A complete description of a molecular reaction requires knowledge of both the position and the momentum of every atom for the entire time it takes for reactants to convert into products. This kind of description falls under the term molecular dynamics (MD).A few simple examples should suffice to demonstrate the critical role that MD plays in chemical reactions. Conservation of momentum must be enforced. Atoms and molecular fragments in motion must maintain their motion unless some barrier or force is applied to them. Consider the reaction of cis-2-butene with Computational Organic Chemistry, Second Edition. Steven M. Bachrach

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“…In the condensed phase, post-TS dynamics simulations can help us to understand the selectivity in organic reactions [32][33][34][35]. Non-statistical and nonequilibrium reaction dynamics often occur at the interface between gases and solids and liquids.…”

Section: Introductionmentioning

confidence: 99%