โ Scribed by Helen Tsai; John D. Roberts
No coin nor oath required. For personal study only.
Proton NMR spectra suggest that the conformation with trans vicinal hydrogens is favored for ephedrine as the free base in deuterium oxide, although in nonโpolar solvents, such as deuteriotrichloromethane, the gauche vicinal hydrogen conformations are favored, as has been reported previously. The conjugate acid has primarily gauche hydrogens. In contrast, the transโhydrogen rotamers of pseudoephedrine dominate for both the nonโprotonated and protonated forms in deuterium oxide. Hydrogen bonding is unlikely to be as important as usually assumed in determining the conformational preferences of these substances.
๐ SIMILAR VOLUMES
The x-ray molecular structures of five chiral phosphoramidates derived from N-phosphorylated nitrogen mustard were determined and the molecular parameters are discussed. The value of the torsion angle of the O=P-N-H function which determines the packing of the molecules was found to determine also t
## Abstract The conformation of 1โphenylโ1โ(1,2โdimethylโ5โpyrrolyl)โ2โ(2โmethylโ5โbenzoylโ1โpyrroly)ethanol, with characteristics of a molecular propeller, is stabilized by intramolecular hydrogen bonding as detected by ^1^H NMR, NOE difference experiments, 2D NMR, COSY, ^13^C NMR, HETCOR, HMBC an