Using pentafluorophenyl as a Lewis acid to stabilize a cis secondary amide conformation.
[reaction: see text]. N-(pyrimidin-2-yl)pentafluorobenzamide adopts a cis amide bond in the solid state with a pyrimidyl nitrogen pointing toward the center of the perfluorophenyl ring. In solution, the compound is a mixture of cis and trans rotamers. The conformational equilibrium is strongly solvent dependent, and the cis rotamer is entropically favored. It is proposed that the entropic driving force is decreased solvation of the two aryl groups when in the cis conformation.
Forbes
C C
CC
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA.
Beatty
A M
AM
Smith
B D
BD
D001549:Benzamides / Q000138:chemical synthesis*; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D013237:Stereoisomerism
D001549:Benzamides; D007202:Indicators and Reagents