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Hydroacridines: Part 23. 1 H and 13 C NMR spectra of sym ‐octahydroacridine, its 9‐(3‐pyridyl) and 9‐(4‐pyridyl) derivatives and the corresponding N (10)‐oxides. An experimental approach to the diamagnetic anisotropy of the pyridine nucleus
Author(s) -
Potmischil Francisc,
Deleanu Călin,
Marinescu Maria,
Gheorghiu Mircea D.
Publication year - 2002
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.996
Subject(s) - chemistry , moiety , chemical shift , nmr spectra database , pyridine , proton nmr , spectral line , proton , carbon 13 nmr , stereochemistry , acridine , crystallography , nuclear magnetic resonance spectroscopy , medicinal chemistry , organic chemistry , physics , quantum mechanics , astronomy
The complete 1 H NMR chemical shift assignments of 1,2,3,4,5,6,7,8‐octahydroacridine ( 1 ), 1,2,3,4,5,6,7,8‐octahydro‐9‐(3‐pyridyl)acridine ( 2 ), 1,2,3,4,5,6,7,8‐octahydro‐9‐(4‐pyridyl)acridine ( 3 ) and the corresponding N (10)‐oxides 1a , 2a and 3a , respectively, were achieved on the basis of 400 MHz 1 H NMR spectra and proton–proton decoupling, HMQC and NOEDIFF experiments. The spectral data for the above compounds provided the first experimental evidence of the difference in the anisotropy effect of the two non‐symmetrical moieties of the pyridine nucleus, and allowed us to ascertain that the shielding effect of the moiety defined by the C(2′)—N—C(6′) atoms is weaker than that of the C(3′)—C(4′)—C(5′) moiety. The 13 C NMR spectra of 1 – 3 and 1a – 3a and the effect of N (10)‐oxidation on the 13 C NMR chemical shifts are also discussed. The N ‐oxidation of 2 and 3 with m ‐chloroperbenzoic acid occurred regiospecifically, affording the N (10)‐oxides 2a and 3a free of N (1′)‐oxide isomers. Copyright © 2002 John Wiley & Sons, Ltd.