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Substituent effects on the ring‐chain tautomerism of some 1,3‐oxazolidine derivatives
Author(s) -
Pihlaja Kalevi,
Juhász Márta,
Kivelä Henri,
Fülöp Ferenc
Publication year - 2008
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3528
Subject(s) - chemistry , substituent , ring (chemistry) , oxazolidine , aryl , tautomer , gas phase , chain (unit) , medicinal chemistry , stereochemistry , mass spectrum , ionization , mass spectrometry , organic chemistry , alkyl , physics , chromatography , astronomy , ion
The 14 and 70 eV electron ionization mass spectra of five sets (R 1 = Me, Et, i ‐Pr, t ‐Bu and Ph) of seven 2‐aryl‐4‐R 1 ‐substituted (Ar = C 6 H 4 X; X = p ‐NO 2 , m ‐Br, p ‐Cl, H, p ‐Me, p ‐OMe and p‐ NMe 2 ) (1–5) and of seven 2‐aryl‐5‐phenyl‐substituted 1,3‐oxazolidines (6; for Ar, see above) were recorded to study their ring‐chain equilibria in the gas phase. These equilibria were also studied by 1 H NMR spectroscopy in CDCl 3 for compounds 5 and 6. A few 2,4‐ and 2,5‐dimethyl‐2‐aryl derivatives (7, 8: Ar = C 6 H 4 X; X = m ‐Br, H and p ‐OMe) were studied both in CDCl 3 and in the gas phase. The main characteristics of the ring‐chain equilibria expressed by the variable Σ RA % of the ring and of the chain form proved to be a strong dependence on the nature of the substituents on C‐2 and C‐4. The results in the gas phase are compared with those in CDCl 3 . Copyright © 2008 John Wiley & Sons, Ltd.