Perturbation of the Degenerate, Concerted Cope Rearrangement by Two Phenyl Groups in Active Positions of (E)-1,4-Diphenylhexa-1,5-diene. Acceleration by High Pressure as Criterion of Cyclic Transition States

1994 ◽  
Vol 116 (10) ◽  
pp. 4289-4297 ◽  
Author(s):  
W. von E. Doering ◽  
Ludmila Birladeanu ◽  
Keshab Sarma ◽  
Joaquim Henrique Teles ◽  
F.-G. Klaerner ◽  
...  
Keyword(s):  
High Pressure ◽  
Transition States ◽  
Cope Rearrangement ◽  
Cyclic Transition

[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.

scholarly journals Study of Chemical LigationVia17-, 18- and 19-Membered Cyclic Transition States

2012 ◽  
Vol 80 (6) ◽  
pp. 821-827 ◽  
Author(s):  
Siva S. Panda ◽  
Claudia El-Nachef ◽  
Kiran Bajaj ◽  
Abdulrahman O. Al-Youbi ◽  
Alexander Oliferenko ◽  
...  
Keyword(s):  
Transition States ◽  
Cyclic Transition

Ligations from Tyrosine Isopeptides via 12- to 19-Membered Cyclic Transition States

2013 ◽  
Vol 78 (15) ◽  
pp. 7455-7461 ◽  
Author(s):  
Vadim Popov ◽  
Siva S. Panda ◽  
Alan R. Katritzky
Keyword(s):  
Transition States ◽  
Cyclic Transition

scholarly journals Ligations of O-acyl threonine units to give native peptides via 5-, 8-, 9- and 10-membered cyclic transition states

ARKIVOC ◽  
2014 ◽  
Vol 2015 (4) ◽  
pp. 9-18
Author(s):  
Siva S. Panda ◽  
Sumaira Liaqat ◽  
Anand D. Tiwari ◽  
Hadi M. Marwani ◽  
Hassan M. Faidallah ◽  
...  
Keyword(s):  
Transition States ◽  
Cyclic Transition ◽  
Native Peptides
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