Conformational analysis of the .delta. receptor-selective, cyclic opioid peptide, Tyr-cyclo[D-Cys-Phe-D-Pen]OH (JOM-13). Comparison of x-ray crystallographic structures, molecular mechanics simulations, and proton NMR data

1994 ◽  
Vol 116 (2) ◽  
pp. 429-436 ◽  
Author(s):  
Andrei L. Lomize ◽  
Judith L. Flippen-Anderson ◽  
Clifford George ◽  
Henry I. Mosberg
Keyword(s):  
Conformational Analysis ◽  
Molecular Mechanics ◽  
Proton Nmr ◽  
Opioid Peptide ◽  
X Ray ◽  
Nmr Data ◽  
Crystallographic Structures ◽  
Delta Receptor

Conformational analysis of acetylcholine and related choline esters

1996 ◽  
Vol 52 (1) ◽  
pp. 184-193 ◽  
Author(s):  
K. Frydenvang ◽  
B. Jensen
Keyword(s):  
Conformational Analysis ◽  
Molecular Mechanics ◽  
Conformational Flexibility ◽  
Accurate Information ◽  
Ammonium Ions ◽  
Molecular Mechanics Calculations ◽  
X Ray ◽  
Quaternary Ammonium Ions ◽  
Choline Esters ◽  
Mm2 Calculations

The crystal structures of carbamoylcholine [2-(carbamoyloxy)-N,N,N-trimethylethanaminium] chloride, bromide and iodide, methoxycarbonylcholine [2-(methoxycarbonyloxy)-N,N,N-trimethylethanaminium] iodide, acetylcholine [2-(acetyloxy)-N,N,N-trimethylethanaminium] chloride and succinylcholine { 2,2′-[(1,4-dioxo-1,4-butanediyl)bis(oxy)]bis(N,N,N-trimethylethanaminium)} iodide have been redetermined at 105 K in order to obtain detailed and accurate information on the geometry of choline esters and to elucidate the conformationally dependent changes of geometry. The conformational flexibility and the preferred conformations are elucidated based on results obtained from X-ray crystallographic studies and molecular mechanics (MM2) calculations. The usefulness of molecular mechanics calculations for quaternary ammonium ions is discussed.

Synthesis, Conformational Analysis and Transannular Reactions of 5,9-Propanobenzo[7]annulene Derivatives

1997 ◽  
Vol 62 (10) ◽  
pp. 1585-1598 ◽  
Author(s):  
Pelayo Camps ◽  
Diana Görbig ◽  
Victoria Muñoz-Torrero ◽  
Francesc Pérez
Keyword(s):  
Conformational Analysis ◽  
Molecular Mechanics ◽  
Related Compound ◽  
Methyl Derivative ◽  
Reaction Conditions ◽  
Molecular Mechanics Calculations ◽  
H Nmr ◽  
Nmr Data ◽  
Acid Catalyzed

(5α,9α,11β)-11-Hydroxy-6,7,8,9-tetrahydro-5H-5,9-propanobenzo[7]annulen-7-one ethylene ketal (6a) and its 11α-methyl derivative (6b) were prepared from monoketal 3. These compounds underwent acid-catalyzed transannular reactions leading to 6,7,8,9-tetrahydro-5H-5,9-propanobenzo[7]annulene derivatives 5a, 8a and 5b, 8b, respectively, depending on the reaction conditions. The compounds 6a and 6b were dehydrated to 6,7,8,9-tetrahydro-5H-5,9-prop[1]enobenzo[7]annulen-7-one (9a) and its 11-methyl derivative (9b), respectively. The conformational analysis of the 5,9-propanobenzo[7]annulene derivatives by molecular mechanics calculations (MM3 program) and the 1H NMR data show that hydroxyketal 6a and the related compound (5α,7β,9α)-6,7,8,9-tetrahydro-5H-5,9-propanobenzo[7]annulen-7-ol (4) exist mainly in the boat-chair conformation with the boat cycloheptenol ring, while for hydroxyketal 6b the chair-boat conformation (chair cycloheptenol ring) seems to be the preferred one.

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