Molecular orbital estimation of the activation enthalpies for intramolecular hydrogen transfer as functions of size of the cyclic transition state and carbon-hydrogen-carbon angle

1991 ◽  
Vol 56 (18) ◽  
pp. 5421-5424 ◽  
Author(s):  
X. L. Huang ◽  
J. J. Dannenberg
Keyword(s):  
Transition State ◽  
Molecular Orbital ◽  
Hydrogen Transfer ◽  
Cyclic Transition ◽  
Cyclic Transition State ◽  
Intramolecular Hydrogen

17α-Hydroperoxypregnenes. IV. A Comparative Study of their Fragmentation by Electron Impact and High Temperature Chromatography

1972 ◽  
Vol 50 (6) ◽  
pp. 706-709 ◽  
Author(s):  
L. Tan ◽  
H. M. Wang ◽  
P. Falardeau
Keyword(s):  
High Temperature ◽  
Transition State ◽  
Electron Impact ◽  
Hydrogen Abstraction ◽  
Fragmentation Pattern ◽  
Common Pathway ◽  
Cyclic Transition ◽  
Cyclic Transition State ◽  
Intramolecular Hydrogen ◽  
High Temperature Chromatography

The fragmentation of 17α-hydroperoxypregnenolone and 17α-hydroperoxyprogesterone by electron impact and thermolysis is described. It is shown that the fragmentation pattern follows a common pathway for both compounds, determined exclusively by the substituents at ring-D. A new reaction in steroid chemistry, termed deoxygenation, is discovered and its mechanism explained by intramolecular hydrogen abstraction via a six-membered cyclic transition state involving the 20-ketone group.

Chemistry of Polynuclear Compounds. IV. The Reduction of Polynuclear Quinones with cyclohexyl-p-toluene Sulphonate

1960 ◽  
Vol 13 (1) ◽  
pp. 103 ◽  
Author(s):  
W Kelly ◽  
JS Shannon
Keyword(s):  
Transition State ◽  
Hydrogen Transfer ◽  
Alternative Methods ◽  
Cyclic Transition ◽  
Polynuclear Compounds ◽  
Cyclic Transition State

In an investigation into the coking mechanism of coal, polynuclear quinones have been adopted as models. Using cyclohexyl-p-toluene sulphonate the following quinones have been reduced to their parent hydrocarbons : dibenzanthrone, isodibenzanthrone, pyranthrone, 4,10-dibromoanthanthrone, anthraquinone (and anthrone), 1,5-dimethoxyanthraquinone, and 1,8-dimethoxyanthraquinone. The reaction gave favourable yields compared with alternative methods, but had the advantage that substituent groups such as halogen and alkoxyl were unattacked. A mechanism is proposed involving complexing of cyclohexyl cations with the quinones, followed by hydrogen-transfer via a resonance-stabilized cyclic transition state.

Seven-membered cyclic transition state in the alkoxy-radical induced intramolecular hydrogen abstraction of 26-hydroxy-furostans

1983 ◽  
Vol 24 (42) ◽  
pp. 4621-4624 ◽  
Author(s):  
Cosme G Francisco ◽  
Raimundo Freire ◽  
Rosendo Hernández ◽  
Maria C Medina ◽  
Ernesto Suárez
Keyword(s):  
Transition State ◽  
Hydrogen Abstraction ◽  
Alkoxy Radical ◽  
Cyclic Transition ◽  
Cyclic Transition State ◽  
Intramolecular Hydrogen

Intramolecular hydrogen atom abstraction with an eight-membered cyclic transition state in open-chain aliphatic aminium radicals

1985 ◽  
Vol 26 (28) ◽  
pp. 3407-3408 ◽  
Author(s):  
Georges Sozzi ◽  
Jean-Pierre Denhez ◽  
Henri Edouard Audier ◽  
Tore Vulpius ◽  
Steen Hammerum
Keyword(s):  
Hydrogen Atom ◽  
Transition State ◽  
Hydrogen Atom Abstraction ◽  
Open Chain ◽  
Cyclic Transition ◽  
Cyclic Transition State ◽  
Intramolecular Hydrogen
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