Amide rule of rotation

Amadori rearrangement, III, 42, 43 Amide rule of rotation, I, 21, 163 Amides, of sugar acids, oxidation of, III, 165... 

Voto6ek has prepared these acids and used the amide rule of rotation for identification of their respective configurations. 

The Amide Rule as formulated by Freudenberg states. The rotation of amides of a hydroxy acids of the D-series is always shifted to the right as compared with the rotation of corresponding hydroxy acids. 

The configuration of C2, the tertiary carbon atom, of o[ -D-isosaccharinic acid has not been established. Unfortunately, application of qualitative rules of configuration based on optical rotation affords disagreeing conclusions in this instance. The positive optical rotation of the phenylhydrazide would indicate the d configuration for C2 on the basis of the phenylhydrazide rule. On the other hand, the reported negative optical rotation of the acid amide would assign the l configuration to this carbon atom on the... 

The characteristic properties of peptides result from the presence of a chain of several or many amide bonds. A first problem is that of numbering, and here Fig. 6.1 taken from the IUPAC-IUB rules may help. A second and major aspect of the structure of peptides is their conformational behavior. Three torsion angles exist in the backbone (Fig. 6.2). The dihedral angle co (omega) describes rotation about C-N,

rotation about N-C , and ip (psi) describes rotation about C -C. Fig. 6.2 represents a peptide in a fully extended conformation where these angles have a value of 180°. 

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