Molecular mechanics (MM2) calculations and cone angles of phosphine ligands

1994 ◽  
Vol 470 (1-2) ◽  
pp. 73-85 ◽  
Author(s):  
Mian Chin ◽  
Gregory L. Durst ◽  
Simone R. Head ◽  
Paul L. Bock ◽  
John A. Mosbo
1988 ◽  
Vol 66 (3) ◽  
pp. 454-460 ◽  
Author(s):  
Michael T. M. Clements ◽  
Ross E. Klinck ◽  
Sriyawathie Peiris ◽  
Arthur J. Ragauskas ◽  
J. B. Stothers

To assess the influence of the conformation of the cyclohexanone moiety in bicyclo[3.2.1]octan-2-ones on the reactivity for β-enolate rearrangement, the behavior of three derivatives under typical homoenolization conditions has been examined for comparison with 3,3-dimethylbicyclo[3.2.1]octan-2-one (1), which was known to be smoothly converted to the [3.3.0] isomer 2. For this purpose, endo-3-tert-butyl-exo-3-methylbicyclo[3.2.1]octan-2-one (8), endo-9-tert-butyl-exo-9-methyl-exo-tricyclo[5.3.1.02,6]undecan-8-one (9), and 9,9-dimethyl-endo-tricyclo[5.3.1.02,6]undecan-8-one (10) were prepared and treated with [Formula: see text] for prolonged periods. Each is much less reactive than 1. The relative orientations of the carbonyl groups with respect to the sites for β-enolization were determined by molecular mechanics (MM2) calculations. 1H/2H exchange in 9 and 10 was also examined under strongly basic conditions at 185 °C.


1996 ◽  
Vol 52 (1) ◽  
pp. 184-193 ◽  
Author(s):  
K. Frydenvang ◽  
B. Jensen

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.


1989 ◽  
Vol 2 (7) ◽  
pp. 573-579 ◽  
Author(s):  
Manton R. Frierson ◽  
Norman L. Allinger

1989 ◽  
Vol 10 (4) ◽  
pp. 503-513 ◽  
Author(s):  
Jenn-Huei Lii ◽  
Steven Gallion ◽  
Charles Bender ◽  
Håkan Wikström ◽  
Norman L. Allinger ◽  
...  

1989 ◽  
Vol 201 ◽  
pp. 363-369 ◽  
Author(s):  
Norman L. Allinger ◽  
James A. Allinger ◽  
L.Q. Yan

1989 ◽  
Vol 86 ◽  
pp. 945-954 ◽  
Author(s):  
F. Bayard ◽  
D. Decoret ◽  
D. Pattou ◽  
J. Royer ◽  
A. Satrallah ◽  
...  

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