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Conformational analysis and 13 C NMR spectra of some 2,6‐diarylpiperidin‐4‐ones
Author(s) -
Hasan Misbah Ul,
Arab Mohammad,
Pandia Rajan K.,
Sekar R.,
Marko Dale
Publication year - 1985
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.1260230503
Subject(s) - chemistry , steric effects , aryl , substituent , ring (chemistry) , chemical shift , molecule , methyl group , chlorine , carbon 13 nmr , nmr spectra database , electronic effect , stereochemistry , proton nmr , crystallography , medicinal chemistry , spectral line , group (periodic table) , organic chemistry , alkyl , physics , astronomy
The 13 C NMR spectra of several methyl substituted 2,6‐diaryl‐4‐piperidones (aryl = phenyl, o‐chlorophenyl) have been measured. Substituent parameters for methyl and chloro groups have also been derived and are discussed in terms of their steric and electronic interactions. Both the methyl substitution at C‐3 and chlorine substitution in the ortho position of the phenyl ring cause significant changes in the 13 C chemical shifts, which can be satisfactorily explained on the basis of steric interactions taking place in the preferred conformations of these molecules. In compounds with o‐chloro groups, the aryl ring is oriented such that the chlorine is syn to the axial hydrogen on the aryl‐bearing carbon. The shielding effect of the carbonyl group is found to be more pronounced on an adjacent equatorial methyl than on an adjacent axial methyl group.