Influence of A(1,3)-strain on the conformational preferences
and stereodynamics of N-formyl-cis-2,6-diarylpiperidines
By:Jeyaraman, R (Jeyaraman, R); Thenmozhiyal, JC (Thenmozhiyal, JC); Murugadoss,
R (Murugadoss, R); Venkatraj, M (Venkatraj, M)
INDIAN JOURNAL OF CHEMISTRY SECTION B-ORGANIC CHEMISTRY INCLUDING MEDICINAL
CHEMISTRY
Volume: 38
Issue: 3
Pages: 325-336
Published: MAR 1999
View Journal Information
Abstract
Ten N-formyl-cis-2,6-diarylpiperidines have been prepared and their preferred conformations are
determined using NMR spectral studies and semiempirical calculations (AM1 and PM3 of MOPAC 6).
The severe A(1,3)-strain due to the interaction between the N-C=O group (coplanar to the C2-N1-C6
plane) and the adjacent aryl group forces the N-formyl-cis-2,6-diarylpiperidines 19-28 to prefer
flattened boat conformations with nitrogen at one of the base positions (VIA and VIE; Figure 1).
Employing variable temperature NMR studies, the barriers for N-C rotation in the N-formylpiperidin-4one 19 and the N-formylpiperidine 28 are found to be 72.5 and 65.8 kJ mol(-1), respectively, which
are in general, lower than those of the corresponding N-nitrosopiperidines. The lower energy barrier
(Delta G(#)) of the N-formylpiperidine 28 compared to the N-formylpiperidin-4-one 19 (by 6.7 kJ mol(1)) is attributed to the larger ground state destabilization of N-formylpiperidine 28 than 19.
Semiempirical calculations show a hydrogen bond type of attraction between the electron-rich oxygen
atom of N-C=O group and the electron deficient hydrogen at alpha-position (H2).
Keywords
KeyWords Plus:SPECTROSCOPY; C-13
Author Information
Reprint Address: Jeyaraman, R (reprint author)
Bharathidasan Univ, Dept Chem, Tiruchchirappalli 620024, India.
Addresses:
[ 1 ] Bharathidasan Univ, Dept Chem, Tiruchchirappalli 620024, India
Publisher
NATL INST SCIENCE COMMUNICATION, DR K S KRISHNAN MARG, NEW DELHI 110 012, INDIA
Categories / Classification
Research Areas:Chemistry
Web of Science Categories:Chemistry, Organic
Document Information
Document Type:Article
Language:English
Accession Number: WOS:000081488300014
ISSN: 0376-4699
Other Information
IDS Number: 217FA
Cited References in Web of Science Core Collection: 18
Times Cited in Web of Science Core Collection: 19