
TY  - JOUR
A1  - Bate, DL 
A1  - Rae, ID 
T1  - Aromatic amides. VIII. Z,E Isomer ratios and stereochemistry about aryl-nitrogen bonds in N-aryl amides and thioamides
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1974
VL  - 27
IS  - 12
SP  - 2611
EP  - 2616
KW  - 
UR  - https://doi.org/10.1071/CH9742611 
N2  - For 4?-substituted 2?,6?-diethylacetanilides, the Z/E isomer ratio depends on the nature of the 4?- substituent, the Z isomer being relatively favoured by electron-withdrawing substituents. The acyla- tion shifts of the ortho aromatic protons for 4?-substituted thiopivalanilides are greatest when the substituent is electron- withdrawing. These relationships complement the previously observed changes in isomer ratios of thioamides and acylation shifts of amides. It is proposed that the Z isomer is more nearly planar when the 4?- substituent is electron-withdrawing. As the substituent becomes more electron-releasing, the amide group is able to twist more out of the ring plane and the Z isomer is destabilized, relative to the E isomer, by n-&#960; electron repulsions. 
ER  -

