Premium
Hydroacridines: part 29. 15 N NMR chemical shifts of 9‐substituted 1,2,3,4,5,6,7,8‐octahydroacridines and their N ‐oxides—Taft, Swain–Lupton, and other types of linear correlations
Author(s) -
Potmischil Francisc,
Marinescu Maria,
Nicolescu Alina,
Deleanu Călin,
Hillebrand Mihaela
Publication year - 2008
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2335
Subject(s) - substituent , chemical shift , chemistry , benzene , stereochemistry , medicinal chemistry , crystallography , computational chemistry , organic chemistry
Abstract The 15 N NMR chemical shifts of 1,2,3,4,5,6,7,8‐octahydroacridine, 12 of its 9‐substituted derivatives, and of the corresponding N ‐oxides were measured and examined in terms of the 9‐substituent effects and the effects of N ‐oxidation. For the 9‐substituent effects, good linear correlations were found with the Taft and Swain‐Lupton substituent constants, for both octahydroacridines and their N ‐oxides. The 15 N chemical shifts of both octahydroacridines and their N ‐oxides also correlate well, linearly with the 13 C chemical shifts of the para ‐carbons in analogously substituted benzene derivatives. Within the studied compounds, the magnitudes of the N ‐oxidation effects range from − 16.4 to − 27.4 ppm (shielding), and also correlate linearly with the Taft and Swain–Lupton substituent constants, as well as with the bond orders of the N + O − bonds in the corresponding N ‐oxides. Furthermore, a very good linear correlation is found between the 15 N chemical shifts of octahydroacridines and those of the corresponding N ‐oxides. From the 15 N chemical shifts data, the Taft and Swain‐Lupton substituent constants for the diacetylamino group (NAc 2 ) were evaluated in the present paper, as follows: σ R = 0.07 and σ I = 0.15; ${{\cal R}} = 0.08$ and ${{\cal F}} = 0.20$ . Copyright © 2008 John Wiley & Sons, Ltd.