
TY  - JOUR
A1  - Yamagami, C 
A1  - Takao, N 
A1  - Takeuchi, Y 
T1  - <sup>15</sup>N Nuclear Magnetic-Resonance Spectra of <I>ortho</I>-Substituted Phenylacetanilides: The Origin of &#947;-<I>syn</I> Effects
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1989
VL  - 42
IS  - 4
SP  - 463
EP  - 469
KW  - 
UR  - https://doi.org/10.1071/CH9890463 
N2  - The 15N chemical shifts of X &#945; and Y &#945;, i.e., the nuclei through which the side chains, X and Y, respectively, of o-substituted phenylacetanilides (2a) are bonded to the aromatic ring were determined. There was observed a uniform upfield shift (&#947;syn effect). In order to explore the origin of the &#947; effect, other o-disubstitutes benzenes (2b-d) were also examined. The values of D, defined as the difference between &#947; &#945; substituent chemical shifts of the ortho (2) and para (3) series of compounds, and considered as a measure of the &#947;-syn effect, were correlated with various electronic and steric substituent parameters. Correlations with electronegativity and van der Waals terms were successful. Examination of the correlations indicated that the &#947;-syn effect is mostly governed by electronegativity. The classic steric compression theory does not seem very convincing as a means of explaining the shielding &#947;-syn effect observed in the present study. 
ER  -

