Conformational Analysis of Open-Chain 1,2:3,4-Diepoxides: Comparison of crystal structures, NMR data, and molecular-orbital calculations

1993 ◽  
Vol 76 (5) ◽  
pp. 1863-1875 ◽  
Author(s):  
Daniel Bur ◽  
Martin Nikles ◽  
Urs Séquin ◽  
Markus Neuburger ◽  
Margareta Zehnder
Keyword(s):  
Conformational Analysis ◽  
Crystal Structures ◽  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Open Chain ◽  
Nmr Data

Conformational analysis of aminovinylpyrazine by semiempirical molecular orbital calculations

1997 ◽  
Vol 33 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Hisayoshi Shiozaki ◽  
Atsushi Oshida ◽  
Dongfeng Hou ◽  
Masaru Matsuoka
Keyword(s):  
Conformational Analysis ◽  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Semiempirical Molecular Orbital

A/C-Ring Colchicine Analogues: a Comparison of Molecular Conformations of the Minimized and Crystal Structures

1997 ◽  
Vol 50 (2) ◽  
pp. 115
Author(s):  
Kiah H. Ang ◽  
Richard J. Greenwood ◽  
Maureen F. Mackay ◽  
Margaret G. Wong
Keyword(s):  
Solid State ◽  
Molecular Mechanics ◽  
Crystal Structures ◽  
Molecular Orbital ◽  
Low Energy ◽  
Molecular Orbital Calculations ◽  
Tubulin Polymerization ◽  
Ring Systems ◽  
Molecular Conformations ◽  
Low Energy Conformations

Molecular mechanics and molecular orbital calculations have been used to determine the low-energy conformations of six biaryl analogues of colchicine lacking the seven-membered B-ring. A comparison of the conformations resulting from the different minimizations has been made, and these conformations were also compared with those found in the solid state for the respective biaryl analogues and the A/C-ring systems of colchicine and isocolchicine. The barriers to rotation about the A/C-linkage of the analogues were estimated from rotational plots. The MM+ calculations were not satisfactory for estimating the barriers, whilst the MMX, MAXIMIN2 and AM1 values, although agreeing on average only to within 16 kJ mol-1 , exhibited the expected trend in magnitude. This trend, however, did not correlate with the inhibition of tubulin polymerization to microtubules.

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