Hydroacridines: part 29. 15N 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

✍ Scribed by Francisc Potmischil; Maria Marinescu; Alina Nicolescu; Călin Deleanu; Mihaela Hillebrand

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 156 KB
• Volume: 46
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.2335

✦ Synopsis

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.