Frontier orbitals along intrinsic reaction coordinates of sulfur-containing [4 + 2] and [8 + 2] cycloadditions

Yamabe, Shinichi; Kawajiri, Satoshi; Minato, Taketoshi; Machiguchi, Takahisa

doi:10.1021/jo00057a026

Cited by 16 publications

(3 citation statements)

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“…This is consistent with results of calculations on hetero-DielsAlder reactions of acrolein, in which there was no tendency toward planar, pseudopericyclic transition structures …”

Section: Referencessupporting

confidence: 91%

Pericyclic and Pseudopericyclic Thermal Cheletropic Decarbonylations: When Can a Pericyclic Reaction Have a Planar, Pseudopericyclic Transition State?¹

1997

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A series of eight thermal cheletropic decarbonylations show dramatic differences in reaction pathways and in activation energies depending on the molecular orbital topology, as calculated by using ab initio molecular orbital theory (MP2(FC)/6-31G* optimized geometries and MP4/D95** + ZPE single point energies). The decarbonylations of 3-cyclopentenone (1) and bicyclo[2.2.1]hepta-2,5-diene-7-one (3) are pericyclic, orbital symmetry allowed reactions, but it is argued that the decarbonylation of cyclopropanone (9), although formally orbital symmetry allowed, lacks an energy of concert and thus is “effectively forbidden”. The carbon monoxide produced from 1 is predicted to be formed vibrationally cool and rotationally hot. Fragmentations of 2,3-furandione (5) and 2,3-pyrroledione (7) are pseudopericyclic reactions with two orbital disconnections, proceed via planar transition structures, and have activation energies that are much lower than expected for pericyclic reactions of comparable exothermicity. It will be an experimental challenge to determine if the carbon monoxide product from each of these is formed with little vibrational or rotational excitation as predicted. Fragmentations of 3H-furan-2-one (11), 3-cyclopentene-1,2-dione (13), and 3-methylene-3H-furan-2-one (15) each have a single disconnection. Strong bonding at the orbital disconnection in the transition structure tends to lower the barrier and give the reaction more pseudopericyclic character.

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“…This is consistent with results of calculations on hetero-DielsAlder reactions of acrolein, in which there was no tendency toward planar, pseudopericyclic transition structures …”

Section: Referencessupporting

confidence: 91%

Pericyclic and Pseudopericyclic Thermal Cheletropic Decarbonylations: When Can a Pericyclic Reaction Have a Planar, Pseudopericyclic Transition State?¹

1997

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“…The reaction profile or PES of the reaction can now be obtained, for example, by plotting the system’s energy as a function of the IRC. Now that IRC calculations for larger systems become feasible, analysis of the IRP becomes an ever increasingly important topic …”

Section: Introductionmentioning

confidence: 99%

Reaction Coordinates and the Transition-Vector Approximation to the IRC

Zeist

Koers

Wolters

et al. 2008

J. Chem. Theory Comput.

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The appearance of a reaction profile or potential energy surface (PES) associated with the reaction path (defined as the path of steepest descent from the saddle point) depends on the choice of reaction coordinate onto which the intrinsic reaction coordinate is projected. This provides one with the freedom, but also the problem, of choosing the optimal perspective (i.e., the optimal reaction coordinate) for revealing what is essential for understanding the reaction. Here, we address this issue by analyzing a number of different reaction coordinates for the same set of model reactions, namely, prototypical oxidative addition reactions of C−X bonds to palladium. We show how different choices affect the appearance of the PES, and we discuss which qualities make a particular reaction coordinate most suitable for comparing and analyzing the reactions. Furthermore, we show how the transition vector (i.e., the normal mode associated with a negative force constant that leads from the saddle point to the steepest descent paths) can serve as a useful and computationally much more efficient approximation (designated TV-IRC) for full IRC computations, in the decisive region around the transition state.

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“…The diradical pathway for chalcogeno-DA reactions has not been examined theoretically, and there are relatively few theoretical investigations of the concerted mechanism. − Thus, we performed a theoretical study of the experimentally important − DA reactions between chalcogen-containing dienes and dienophiles including sulfur, selenium, and tellurium compounds (reactions 2−6, Scheme ). The competition between the stepwise diradical and concerted pathways in the chalcogeno-DA reactions is the major focus of this investigation.…”

Section: Introductionmentioning

confidence: 99%

Competition between Diradical Stepwise and Concerted Mechanisms in Chalcogeno-Diels−Alder Reactions: A Density Functional Study

Orlova

Goddard

2001

J. Org. Chem.

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The chalcogeno-Diels-Alder reactions of H(2)C=X (X = S, Se, Te) with butadiene, with trans,trans- and cis,trans-2,4-hexadiene, as well as of ethylene with thio-, seleno-, and telluroacrolein and reactions of thioformaldehyde with thioacrolein are examined theoretically. The B3LYP exchange-correlation functional with the 6-31G(d) and LanL2DZ(d) basis sets is employed. Stepwise diradical and concerted pathways are considered for all reactants. A modified concerted mechanism via a pre-reaction complex followed by a concerted transition state is studied for thioformaldehyde reacting with thioacrolein. The stepwise diradical pathways are predicted to be energetically less favorable than the concerted pathways for all cases considered. Even the sterically hindered reaction between selenoformaldehyde and cis,trans-2,4-hexadiene prefers a concerted path. It is a considerable challenge to reverse this energy preference for the concerted reaction given that both electronic and steric factors act to increase or decrease the activation energies of the concerted and diradical stepwise paths in the same way. A modified concerted mechanism operates for reagents with very small HOMO-LUMO gaps such as thioformaldehyde and thioacrolein. This mechanism is completely synchronous, with a vanishingly small barrier.

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Frontier orbitals along intrinsic reaction coordinates of sulfur-containing [4 + 2] and [8 + 2] cycloadditions

Cited by 16 publications

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Pericyclic and Pseudopericyclic Thermal Cheletropic Decarbonylations: When Can a Pericyclic Reaction Have a Planar, Pseudopericyclic Transition State?¹

Pericyclic and Pseudopericyclic Thermal Cheletropic Decarbonylations: When Can a Pericyclic Reaction Have a Planar, Pseudopericyclic Transition State?¹

Reaction Coordinates and the Transition-Vector Approximation to the IRC

Competition between Diradical Stepwise and Concerted Mechanisms in Chalcogeno-Diels−Alder Reactions: A Density Functional Study

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Frontier orbitals along intrinsic reaction coordinates of sulfur-containing [4 + 2] and [8 + 2] cycloadditions

Cited by 16 publications

References 0 publications

Pericyclic and Pseudopericyclic Thermal Cheletropic Decarbonylations: When Can a Pericyclic Reaction Have a Planar, Pseudopericyclic Transition State?1

Pericyclic and Pseudopericyclic Thermal Cheletropic Decarbonylations: When Can a Pericyclic Reaction Have a Planar, Pseudopericyclic Transition State?1

Reaction Coordinates and the Transition-Vector Approximation to the IRC

Competition between Diradical Stepwise and Concerted Mechanisms in Chalcogeno-Diels−Alder Reactions: A Density Functional Study

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Product

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Pericyclic and Pseudopericyclic Thermal Cheletropic Decarbonylations: When Can a Pericyclic Reaction Have a Planar, Pseudopericyclic Transition State?¹

Pericyclic and Pseudopericyclic Thermal Cheletropic Decarbonylations: When Can a Pericyclic Reaction Have a Planar, Pseudopericyclic Transition State?¹