Effect of terminal fluorine substitution on the Cope rearrangement: boat versus chair transition state. Evidence for a very significant fluorine steric effect

1993 ◽  
Vol 115 (20) ◽  
pp. 9349-9350 ◽  
Author(s):  
William R. Dolbier ◽  
Keith W. Palmer
Keyword(s):  
Transition State ◽  
Steric Effect ◽  
Cope Rearrangement ◽  
Fluorine Substitution

scholarly journals Transient [3,3] Cope rearrangement of 3,3-dicyano-1,5-dienes: computational analysis and 2-step synthesis of arylcycloheptanes

2018 ◽  
Vol 9 (46) ◽  
pp. 8760-8764 ◽  
Author(s):  
Ehsan Fereyduni ◽  
Jacob N. Sanders ◽  
Gabriel Gonzalez ◽  
K. N. Houk ◽  
Alexander J. Grenning
Keyword(s):  
Transition State ◽  
Computational Analysis ◽  
Cope Rearrangement ◽  
State Analysis

Unexpectedly mild [3,3] rearrangement computed transition state analysis, regio- and diastereoselecitve transformations multicomponent couplings, convergent 2-step arylcycloheptene synthesis.

Anion-Accelerated Aromatic Oxy-Cope Rearrangement in Geranylation/Nerylation of Xanthone: Stereochemical Insights and Synthesis of Fuscaxanthone F

Synlett ◽  
2020 ◽  
Vol 31 (14) ◽  
pp. 1378-1383
Author(s):  
Takashi Matsumoto ◽  
Yuuki Fujimoto ◽  
Kanae Takahashi ◽  
Ryouma Kobayashi ◽  
Haruhiko Fukaya ◽  
...  
Keyword(s):  
Transition State ◽  
Side Chain ◽  
Cope Rearrangement ◽  
State Structure ◽  
Transition State Structure

An efficient installation of a 3,7-dimethylocta-2,6-dien-1-yl (geranyl or neryl) side chain at the C(1) position of a xanthone core by utilizing an anion-accelerated aromatic oxy-Cope rearrangement is described. Experiments revealed that this uncommon rearrangement takes place in a stereospecific manner through a chair-like transition-state structure. An application to the syntheses of the natural xanthone fuscaxanthone F, possessing a geranyl side chain, and its neryl analogue is also described.

The Influence of the 2-Alkoxy Group and of C-5 Substituents on the Direction of Reductive Cleavage of 2-Alkoxytetrahydrofurans by AlH2Cl in Ether Solution

1972 ◽  
Vol 50 (10) ◽  
pp. 1502-1512 ◽  
Author(s):  
P. C. Loewen ◽  
Miss L. P. Makhubu ◽  
R. K. Brown
Keyword(s):  
Transition State ◽  
Alkyl Group ◽  
Steric Effect ◽  
Bond Cleavage ◽  
Alkoxy Group ◽  
Ring Cleavage ◽  
Relative Ease ◽  
Ether Solution ◽  
A Minor ◽  
Minor Extent

The AlH2Cl hydrogenolysis of ether solutions of 2-alkoxytetrahydrofurans in which the alkoxy group is either CH3O, C2H5O, i-C3H7O, or t-C4H9O, gives only those products resulting from ring C—O bond cleavage. However, substituents at C-5 of 2-methoxytetrahydrofuran exert a strong effect on the ratio of ring to exo C—O bond cleavage. Thus, alkyl (electron donor) groups at C-5 promote an increase in the amount of exo cleavage, the proportion increasing from 62.5 to 100% as the C-5 alkyl group is changed from CH3 to t-C4H9. In contrast, electron withdrawing substituents, CH3OCH2— and C6H5, at C-5 favor ring cleavage to the extent of 93 and 84% respectively.The results are interpreted in terms of the influence that these substituents exert through their electronic properties on the relative ease of attainment of the transition state leading to either ring C—O or exo C—O bond cleavage. However, evidence is provided to show that the bulk steric effect of these substituents also controls, though to a minor extent, the proportion of ring to exo cleavage.

ChemInform Abstract: AB INITIO CALCULATION OF THE TRANSITION STATE FOR THE COPE REARRANGEMENT

1984 ◽  
Vol 15 (36) ◽  
Author(s):  
Y. OSAMURA ◽  
S. KATO ◽  
K. MOROKUMA ◽  
D. FELLER ◽  
E. R. DAVIDSON ◽  
...  
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Ab Initio Calculation ◽  
Cope Rearrangement
Sign in / Sign up

Export Citation Format

Share Document