Additions and Corrections - Diastereomeric Transition States. High and Low Energy Reaction Pathways in the Cope Rearrangement.

1978 ◽  
Vol 100 (9) ◽  
pp. 2936-2936
Author(s):  
Kenneth Shea ◽  
Richard Phillips
Keyword(s):  
Transition States ◽  
Low Energy ◽  
Reaction Pathways ◽  
Cope Rearrangement ◽  
Energy Reaction

Electron-stimulated desorption of O− from O2 adsorbed on CD3CN: substrate-mediated low-energy reaction pathways

1999 ◽  
Vol 305 (5-6) ◽  
pp. 408-412 ◽  
Author(s):  
Moustapha Lachgar ◽  
Yvonnick Le Coat ◽  
Roger Azria ◽  
Michel Tronc ◽  
Eugen Illenberger
Keyword(s):  
Low Energy ◽  
Reaction Pathways ◽  
Electron Stimulated Desorption ◽  
Energy Reaction

[3,3] Sigmatropic Rearrangement of Some Fluorinated 1,5-Hexadienes

2002 ◽  
Vol 67 (10) ◽  
pp. 1517-1532 ◽  
Author(s):  
William R. Dolbier ◽  
Keith W. Palmer ◽  
Feng Tian ◽  
Piotr Fiedorow ◽  
Andrzej Zaganiaczyk ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Transition States ◽  
Activation Parameters ◽  
Sigmatropic Rearrangement ◽  
Semiempirical Methods ◽  
Cope Rearrangement ◽  
Computational Studies ◽  
Stepwise Mechanism ◽  
Radical Intermediates

Fluorine atoms incorporated into 1,5-hexadiene molecule should influence the kinetic as well as the thermodynamic parameters of [3,3] sigmatropic rearrangement (Cope rearrangement). Within few decades is has been documented that this transformation proceeds in a concerted manner, rather than stepwise with some radical intermediates involved. Few new terminally fluorinated 1,5-hexadienes (compounds 3, 5A, 7, 9 and 5B) have been synthesized. The activation parameters of rearrangement have been determined and compared with those known for hydrocarbon analogues. While systems developing chair-like transition states (compounds 3 and 5) showed close similarity with hydrocarbon analogues (compound 1), those developing boat-like transition states (compounds 7, 9 and 5B) may proceed through radical stepwise mechanism. Computational studies of the transition states were carried out, showing that only ab initio methods (MP2 and especially DFT) can give approximate correlation with experimental data, whereas in the case of hydrocarbon analogues even simple semiempirical methods (AM1) were reliable enough to reproduce experimental results.

Ambident reactivity in the reaction of phenoxide ion with 2-N-(2′,4′-dinitrophenyl)- and 2-N-(4′-nitrophenyl)-4,6-dinitrobenzotriazole 1-oxides, new superelectrophiles

1988 ◽  
Vol 66 (7) ◽  
pp. 1712-1719 ◽  
Author(s):  
Erwin Buncel ◽  
Julian M. Dust
Keyword(s):  
Activation Energy ◽  
Adduct Formation ◽  
Reaction Pathways ◽  
Resonance Spectroscopy ◽  
The Novel ◽  
Reaction Series ◽  
Bond Scission ◽  
Energy Reaction ◽  
Successive Removal ◽  
Ambident Nucleophile

Reaction of the novel superelectrophiles 2-N-(2′,4′-dinitrophenyl)- and 2-N-(4′-nitrophenyl)-4,6-dinitrobenzotriazole 1-oxides, 3, and 4, possessing two electrophilic centres, with the ambident nucleophile potassium phenoxide in (CD3)2SO was followed by 400 MHz 1H nuclear magnetic resonance spectroscopy. A dichotomy in the reaction pathways has been observed. With MeO−, attack at C-7 leads to reversible adduct formation, while attack at C-1′ results in irreversible N-2: C-1′ bond scission via the metastable C-1′ adduct. In contrast, the reaction of 3 and 4 with PhO− proceeds by a two-pronged attack: formation of C-7 carbon-bonded phenoxide adducts via the ortho and para carbon sites, and oxygen-based cleavage products by attack at the C-1′ position, accompanied by N-2:C-1′ bond scission, in accord with the ambident reactivity of PhO−. Significantly, in this case reaction of both C-7 and C-1′ is effectively irreversible. Moreover, the reaction of phenoxide with either 3 or 4 shows striking differences compared to the reaction of PhO− with 2-N-(picryl)-4,6-dinitrobenzotriazole 1-oxide, 1. Reaction of PhO− with 1 resulted only in O-attack at C-1′ and N-2:C-1′ bond scission; there was no evidence for C-7 adduct formation via O- or C-attack. This marked difference in behaviour can be attributed to the decreased susceptibility to C-1′ attack exhibited by 3 and 4 as compared to 1 and arises from the successive removal of electron-withdrawing nitro groups from the 2-N′-nitroaryl moiety in the series 1 → 3 → 4. The reactions are discussed on the basis of selectivity considerations and an activation energy/reaction coordinate profile comparing the pathways for both C-attack at C-7 and O-attack at C-l′ as electrophilicity (delocalizability) is progressively modulated in the reaction series.

scholarly journals Finding Reaction Pathways and Transition States: r-ARTn and d-ARTn as an Efficient and Versatile Alternative to String Approaches

2020 ◽  
Vol 16 (10) ◽  
pp. 6726-6734 ◽  
Author(s):  
Antoine Jay ◽  
Christophe Huet ◽  
Nicolas Salles ◽  
Miha Gunde ◽  
Layla Martin-Samos ◽  
...  
Keyword(s):  
Transition States ◽  
Reaction Pathways

Extrapolation of low-energy reaction cross sections

1976 ◽  
Vol 269 (1) ◽  
pp. 61-73 ◽  
Author(s):  
J.E. Monahan ◽  
A.J. Elwyn ◽  
F.J.D. Serduke
Keyword(s):  
Cross Sections ◽  
Reaction Cross ◽  
Low Energy ◽  
Energy Reaction ◽  
Reaction Cross Sections
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